1974 Corvette guide: the split rear bumper, the 454's last year and how to check one

The nose went soft for 1973 and the tail followed. “The transition to ‘soft’ bumpers was completed in 1974,” the Black Book says: a body-color urethane skin over an aluminum impact bar on two telescopic brackets. GM’s list of standard features puts it first, as a “Resilient body-colored urethane rear bumper cover and recessed taillights”. GM’s own paper never mentions a seam or two pieces. Those details are the Black Book’s.

The one-year claim rests on the cars either side. The 1973 kept its chrome rear bumper (1973 kit), and the 1975 Black Book page describes a one-piece skin, unlike the 1974’s two pieces, with pads added at the corners. Hagerty’s buyer’s guide calls the split rear “a one-year-only design” (opens in new tab) and its valuation page says every later bumper was one piece. Owners agree (CorvetteForum, 2008, 2009 and 2023). The word “only” is theirs; GM never wrote it.

Why does a 1974 Corvette have a split rear bumper? No source this site read gives GM’s reason, so this page doesn’t guess. What they agree on is the result: body-color urethane in two pieces, joined down the middle.

The nose gives nothing away. Owners say the 1973 and 1974 front covers both run straight across with no bumper pads, and 1975-on covers have them.

Age is the problem. Owners in a 2008 thread said original 1974 rear covers wave and crack, that many were replaced long ago with one-piece fiberglass or later C3 covers, and that fiberglass reproductions with a false split exist (opens in new tab). On Bring a Trailer, a genuine LS4 coupe sold in October 2025 wore “a later-style one-piece rear bumper cover”, and the year’s top 2026 sale had both covers replaced by its selling dealer, the rear one, a commenter said, a one-piece unit with a faux seam. A replaced cover costs a 1974 little, owners say. Ask why it was replaced, though: rear damage is the usual reason.

So a seam proves a 1974 look, a missing one disproves nothing, and the VIN decides.

“This was the last year for 454ci ‘big block’ engines in Corvettes,” the Black Book says (page 7), and the C3 guide agrees.

Was 1974 the last big-block Corvette? Yes. The LS4 454 made 270 hp at 4,400 rpm and 380 lb-ft at 2,800 rpm, SAE net, on 8.25:1 compression (power teams): 5 hp and 15 lb-ft down on the 1973’s LS4. For 1975 there was no big-block at all. It cost $250 by the Black Book’s figure and $264 on GM’s May 15, 1974 list, the heavy-duty battery included, and 3,494 buyers took it, 9.3 percent of the year (this site’s arithmetic). GM’s specification form marks the LS4 for all states and the Black Book lists California codes for it, so a California car could have one.

GM’s optional-equipment weights charge it 200 lb, 178 of them on the front wheels, on top of a base coupe GM puts at 3,390 lb at the curb.

The converter was the other thing on its way out. “These were the last Corvettes without catalytic converters,” the Black Book says, and the 1975 Corvette guide covers what replaced them. GM’s 1974 emission controls were air injection at the exhaust ports (on every engine except the L48 automatic outside California) and exhaust gas recirculation, with no converter anywhere on the form. GM’s form gives the fuel as “Unleaded or low lead”; the Black Book says 91-octane leaded or low-lead regular.

Points ignition and a mechanical tach went too. GM’s form lists conventional ignition, “Transistorized: not available”, and a “Mechanical tachometer” (page 75). For 1975, HEI and an electronic tach arrived together.

How much horsepower does a 1974 Corvette have? 195 hp from the standard L48, 250 hp from the L82 and 270 hp from the LS4, GM’s SAE net ratings, each with a single four-barrel and dual exhaust:

The L82 earned its price inside. GM’s crankshaft page gives it a forged steel crank, where the L48 and LS4 make do with cast nodular iron, and 16 bolts on its five main caps against their 10. Owners add that L82s wore finned aluminum valve covers and the others painted steel ones (CorvetteForum, 2021).

The four-speed that changed during the year

The M20 wide-ratio four-speed was standard. The M21 close-ratio box cost nothing either, but not with the L48. The M40 Turbo Hydra-matic automatic was free with the L48 and extra with either optional engine: $97 early in production, $103 by the Black Book’s later figure, $113 on GM’s May list. Two in three buyers (25,146 cars, 67.1 percent) took it.

GM’s paper shows the four-speeds changing mid-year. The specification form issued in September 1973 gives the wide-ratio box as 2.52, 1.88, 1.46, 1.00 and the close-ratio as 2.20, 1.64, 1.27, 1.00, with the LS4 offered with either (page 50). The same form, revised in January 1974, gives 2.64, 1.75, 1.33, 1.00 and 2.43, 1.61, 1.23, 1.00, and says the wide-ratio box is available with every engine “except V8-454” (page 76). January 1974 is when GM revised the form, not a documented date for the change on the line.

GM doesn’t name the new gearbox’s maker. Corvette Action Center says a Borg-Warner Super T-10 replaced the Muncie for 1974, and owners agree that early cars had Muncies and late ones Borg-Warners. They don’t agree when: “between Feb/March” in one 2006 thread, May or June in a 2020 one. The quick tell, by owners’ account, is the side cover: seven bolts and a flat bottom edge on a Muncie, nine bolts and a curved edge on a Borg-Warner (opens in new tab).

The Black Book’s M21 count, 3,494, exactly matches the LS4’s. Some LS4s were automatics, so that looks like a repeated figure, and this page doesn’t use it.

Axles. Positraction, Chevrolet’s limited-slip differential, came with every one: 3.36 standard behind an L48 or LS4 four-speed, 3.08 behind their automatics, 3.55 or 3.70 on an L82, by GM’s revised power teams. Another ratio cost $12, on 1,219 cars.

Z07 and FE7. Z07, the off-road suspension and brake package, cost $400 with the L82 or LS4 and the M21 only, and brought heavy-duty power brakes front and rear. The Black Book counts 47 (Hagerty prints 40). FE7, the Gymkhana suspension, was a $7 stiffer front anti-roll bar and springs with no order restrictions, on 1,905 cars.

Two sets of prices survive, and both are right. The Black Book’s 1974 page gives the coupe $6,001.50 and the convertible $5,765.50, a figure Hagerty repeats. GM’s own price list, “effective with vehicles shipped on and after May 15, 1974”, asks $6,081.50 and $5,845.50. The Black Book’s figure can’t be dated (its own note gives the automatic two prices), so a window sticker showing either can be genuine. For scale, GM’s 1973 coupe was $5,561.50 and its 1975 coupe $6,810.10.

Buyers spent on comfort. Counts and the first price column are the Black Book’s; the second is GM’s May 15, 1974 list:

Power steering went on 95.8 percent of 1974s, air conditioning on 78.4 percent and leather on more than half (this site’s arithmetic): saddle 9,334, black 7,828, silver 2,797, by Corvette Action Center’s split.

YJ8 cast aluminum wheels appeared on early 1974 option lists, the Black Book says, but Chevrolet’s records show none sold. Every 1974 left on 15 × 8 steel wheels painted silver, with trim rings and center caps, on GR70-15 steel-belted radials. Aluminum wheels came back for 1976 (the 1976 Corvette guide has the story), so a 1974 on alloys is wearing later or aftermarket ones.

Is 1974 a good year for the Corvette? For a buyer who wants the last big-block, the last car without a converter or the split tail, yes. For speed, no. These were comfort cars, and the order sheet shows buyers knew it.

Eight new colors, and leather in three

GM’s color and trim chart, revised August 17, 1973, lists ten:

The Black Book prints the same codes with a 9 in front (980 for Corvette Orange). Every color but Classic White and Mille Miglia Red was new for 1974, per Corvette Action Center. Neither source counts cars by color. Soft tops came in black or white.

Standard vinyl came in black, midnight blue, light neutral, dark red, medium saddle and silver. The custom interior added leather seat trim, cut-pile carpet and wood-grain accents on the doors and console, in black, saddle or silver only. Convertible buyers were held to GM’s chart: “the only combinations that have been approved”.

Smaller changes, per the Black Book: a redesigned radiator for better cooling at low speed, lap and shoulder belts joined with a lock that worked by deceleration, the alarm switch moved from the rear panel to the driver’s fender, magnets in the power steering to catch debris in the fluid, and a ten-inch inside mirror.

How do I tell a real 1974 454? Read the VIN plate on the left windshield pillar, not the title: owners have seen titles with typos where the engine letter should be (CorvetteForum, 2013). GM’s service pages lay out the order, and the Black Book fills in the 1974 codes:

A Z in fifth place makes a factory LS4. A J under a big-block hood makes a swap, however good it is.

The engine pad sits at the front of the block on the right side (GM’s location chart). It carries the plant, the build month and day and a three-letter suffix; on an original engine, owners say, a VIN derivative too. The Black Book’s suffixes:

The castings: block 3970010 and head 333882 on both 350s, block 3999289 and head 336781 on the 454. A matching casting isn’t proof of an LS4. Owners say the 3999289 block also went into 1973 trucks and motor homes (CorvetteForum, 2017), so the pad suffix and the derivative do the work.

Dating a 1974. The Black Book’s month-end serials place a car in its build month:

No serial moved in July. Owners say a strike shut St. Louis from late June 1974 (CorvetteForum, 2016–2021); no GM document this site read mentions one. The Black Book files the last 4,245 cars under August.

The trim plate, with the body number, trim and paint codes, is on the upper left door hinge pillar, by GM’s chart. Check its codes against the paint and seats in Eight new colors, and leather in three. The axle code is on the bottom of the carrier, at the cover flange.

What gets faked. Badges first: a 454 hood emblem, an L82 hood emblem or finned valve covers prove nothing. Owners add that luggage racks were dealer-installed (CorvetteForum, 2021).

NHTSA’s complaint file (opens in new tab) holds nothing for a 1974 (October 22, 2026). It starts in September 1994, so that silence says nothing about how these cars behaved new.

The recall. GM recall 74V050000, Chevrolet campaign 74-C-13, reported to NHTSA on March 25, 1974: the fuel tank return line fitting could have a thin wall that might break. Fuel returning to the tank would then spill near the tailpipe outlet with the engine running, where a backfire or sparks could light it. The fix was to inspect the lines and replace them as needed, and the campaign record (opens in new tab) counts 2,937 potential units. NHTSA can’t say whether a given car was done, so look at the fitting. The year’s other recall entries cover aftermarket calipers and oil filters.

Chevrolet’s dealer bulletins, transcribed by Corvette Action Center, add four more:

• 74-T-6 (December 5, 1973): blocked heads. Casting flash could block a coolant port in head casting 333882, the 1974 small-block head, on a small number of 350 and 400 V8s built before September 24, 1973, overheating them within minutes. By now that’s history, not a buying risk.
• 74-T-29 (May 1, 1974): soft pushrod guides. Addressed to 1974 Chevrolet cars and light trucks with the 454, the Corvette’s LS4 among them: a loud ticking could mean worn soft guides letting the pushrods wander. It lists engine codes T1030, T1031, T1101, T1102 and T1105 (late October and early November 1973 builds, by this site’s reading) and says to file-test all eight guides and replace soft ones (opens in new tab).
• 75-T-3 (January 17, 1975): the speedometer. On 1974–1975 four-speed cars, a dead speedometer could mean a stripped driven gear, from friction in the adapter. Chevrolet released a low-friction adapter (GM 1565211, OEM) and key (GM 6476870, OEM).
• 77-T-48 (July 1977): torque shake. On 1973–1977 cars, the steering wheel, floor and seat could shake at about 55–60 mph under power. The cure was resetting rear camber.

The urethane. The rear cover is the 1974’s own weak spot (see A tail in two halves), and the nose is the same straight-across urethane the 1973 Corvette guide describes crumbling with age.

Everything else (frame and birdcage rust, T-top and windshield leaks, vacuum headlights, calipers, rear wheel bearings) is the C3’s, covered in Known C3 problems in the C3 buyer’s guide. The 1974 floor is fiberglass; the steel floor that rusts came in 1976. The birdcage is steel either way.

1. The frame and birdcage first, by the C3 checklist: the rear kick-ups, the #2 body mounts behind the kick panels and the lower windshield corners. A rotten cage outweighs every other point here.
2. The VIN plate, not the title: 37 or 67, then J, T or Z, before paying for a convertible or an engine.
3. The engine pad: a suffix that matches the engine and gearbox (a CW suffix on an LS4), and the VIN derivative if it’s there.
4. The rear cover. A seam, no corner pads, no waves or cracks. If it’s a later or reproduction cover, ask why it was replaced and look for rear damage underneath.
5. The fuel return line fitting, for recall 74-C-13’s thin wall, and any smell of fuel near the tailpipes.
6. On an LS4, listen for ticking from the valve train at idle (74-T-29).
7. On a four-speed, the speedometer (75-T-3), and the side cover against the build date: a Muncie early, a Borg-Warner late.
8. A drive past 55 mph under power, for torque shake.
9. On a convertible, the top and its frame, and any hardtop; on a coupe, the roof panels and their seals. Damp carpet means leaks, and leaks feed the birdcage.
10. The paperwork: a window sticker or build sheet beats any badge. Then an inspection on a lift by a shop that knows C3s.

How much is a 1974 Corvette worth today? On Bring a Trailer (opens in new tab), five 1974s were listed between January 1 and October 21, 2026, and four sold. That’s too few for a median worth printing, so here are all four (this site’s count of sold prices, without the buyer’s fee, with the engine read from each VIN):

Widen the window to all of 2025 and 2026 and 15 sold, median $16,250. Five convertibles made a median of $22,000 ($14,000 to $33,000), and the ten not titled as convertibles $15,250 ($11,250 to $51,500). In 2025 alone, 11 sold at a median of $16,000.

The 454s are where the lessons are. Of the four 1974s sold with a 454 named in the listing, two were J-VIN cars: the March coupe above, and a coupe titled “454-Powered” that sold for $11,250 in September 2025 with a “replacement 454ci V8” in its description. The two genuine Z-VIN LS4s brought $16,000 (a coupe, October 2025) and $33,000 (the July convertible); two more Z cars were bid to $36,500 and $14,900 in 2025 without selling. No L82 sold in either year.

Hagerty’s price guide (opens in new tab), as the Internet Archive captured it, put a #3 (Good) L48 coupe at $14,100 (April 2025), the newest public figure this site could read; a newer one may exist. Its adjustments: plus $500 for the close-ratio four-speed, minus 8 percent for an automatic, plus $1,000 for air conditioning and plus $2,500 for power steering. Hagerty’s public figure covers only that coupe, and classic.com offered no 1974 figure this site could read.

For scale, this site’s 2026 medians are $20,300 for the 1973 and $14,250 for the 1975 (9 sold each). On these small samples, 1974 coupes sit between the two. These are sales, not a forecast.

For the history, a Z-VIN LS4 four-speed with its paperwork. This is the car the year exists for: one of 3,494, the last big-block Corvette, breathing through no converter. Bring a Trailer’s two genuine LS4 sales across 2025 and 2026, $16,000 and $33,000, are too few to price one. Spend instead on proof: the Z, a CW suffix on the pad, a valve train that doesn’t tick (74-T-29) and a window sticker if one survives. A 454 badge adds nothing to that sum.

For the drive, a small-block four-speed coupe with its split tail intact. Leave the big-block out and the car sheds 200 lb, 178 of it off the nose. An L82 adds the forged crank and 55 hp over the L48, so look for the T. And keep an original two-piece cover if the car has one: they only get scarcer.

For the least money, a sound L48 automatic coupe near the $15,250 coupe median. Two in three 1974s left with the automatic, and a 350 with 195 hp is begging for headers and a cam. Of course it’ll get them, and nothing rare is lost when it does.

A rotted birdcage is a rebuild with a car attached: price it that way or walk. And never pay LS4 money for a J car with a big-block in it. Get the VIN and the steel right, and you own the last year America’s sports car came with a big-block on the order sheet, for well under the $39,000 median the C3 guide found for 1968–1972 cars.