1973 Pontiac Firebird Trans Am SD-455
F-body · The SD-455 (Super Duty 455) was a surprise performance engin... · The last fire breather — Super Duty 455 defied the emissions era
Ultra Rare
Production & Overview
Total Production
4,802
Original MSRP
N/A
Assembly Plants
Norwood, OH
Wheelbase
108.1 inches
Body Styles
Sport Coupe
Curb Weight
3,655 lbs
Notable Packages & Production
Super Duty 455 — SD455
Secret performance engine — round port heads, forged pistons, 4-bolt mains. Last true Pontiac performance engine.
6-10x standard TA
252
produced
Available Engines
L75 455ci — V8
Standard Trans Am 455 — emissions era detuned
250 hp
L82 455ci — V8
Super Duty 455 — round port heads, forged internals, factory race engine. Net 290hp significantly underrated — actual output closer to 400hp gross.
290 hp
Buyer Checklist
⚠ Clone warning: SD-455 matching numbers is mandatory for full value. Non-matching SD-455 loses 50-60% of premium. PHS essential.. Always verify with cowl tag, engine stamp, and registry before purchase.
PHS documentation mandatory for SD-455 claim
SD-455 engine has specific suffix codes — verify carefully
Round port heads are key identifier of SD-455
Firewall tag must show SD-455 option code
F-body frame rail rust
Floor pan rust
Shaker scoop originality
Only 252 produced — every one is documented, cross-reference registry
4-speed vs automatic — both correct, 4-speed more desirable
Known Problem Areas
Standard 455 presented as SD-455 — most common fraud
Frame rail rust
SD-455 engine swaps from wrecked cars into standard Trans Ams
Floor pan rust
What Drives Value
↑ Increases Value
SD-455 matching numbers with PHS and registry confirmation
4-speed SD-455
Low mileage documented
↓ Decreases Value
Fake SD-455 without documentation
Frame rust
Non-matching engine
Restoration Overview
Difficulty
Hard — SD-455 parts scarce
Parts Availability
Moderate — second gen F-body body parts good, SD-455 engine parts difficult
Driver Quality Cost
$35,000 – $70,000
Show Quality Cost
$90,000 – $200,000
Key Suppliers
Year One · Ames Performance · PY Classic Pontiac · Pontiac SD-455 specialists
Pop Culture & Legacy
SD-455 was developed in secret while GM officially retreated from performance
Car and Driver tested the SD-455 Trans Am and called it one of the best performance cars of the era
Last truly powerful factory Pontiac engine — the end of an era
Only 252 produced in 1973 — every car is known and documented
Other Pontiac Firebird Trans Am SD-455 Years