Frequently Asked Questions
Find answers to Frequently Asked Questions for First Generation Firebirds that have been asked and answered on FGF. Special thanks needs to be given to all the FGF members who took the time to respond to other member's questions.
Engine - Codes
Short answer: The engine, transmission, and component codes for a 1968 Firebird 350 H.O. are below.
| Engine | Code | Output |
|---|---|---|
| 350 H.O. Manual | WK | 320 hp, 10.5:1 |
| 350 H.O. Automatic | YM | 320 hp, 10.5:1 |
| Transmission | Maker | Code |
|---|---|---|
| 3-speed standard (column shift) | Saginaw | RJ |
| 3-speed standard (floor shift) | Dearborn | DB |
| 4-speed optional | Muncie | FX |
| 2-speed automatic | ST-300 | MB |
| 2-speed automatic (w/ A/C) | ST-300 | MC |
Other components: Cylinder heads “18” · Carburetor: MT 7028269 / AT 7028266 · Intake manifold (same as all 4-bbl): 9790140 · Exhaust manifolds (same as Std. & 400): 9794320 RH / 9777755 LH · Distributor: MT 1111447 / AT 1111282.
For reference, 2,087 400 H.O. Firebirds were made in 1968; the 350 H.O. count is likely similar or a bit lower.
Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.
Content last modified: June 13, 2026 at 10:06 am
Short answer: That number near the distributor is the block casting number — the full number is 9786133, which denotes a 1967 400 cid block (it’s like a part number, not the sequential build/serial number, which is on the front passenger side). Source: Pontiac Muscle Car Performance 1955–1979 by Pete McCarthy.
Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.
Content last modified: June 13, 2026 at 10:06 am
Short answer: Here’s how that set of engine/carb/manifold markings decodes:
- YR — engine usage/type code
- 33202 — Engine Unit Number
- 23N108627 — partial VIN, unique to the car the engine came from
- E220 (on the intake) — a date code (e.g., May 22, 1970?)
- 9796155 (on the exhaust manifold) — a part/casting number
- 17054905 — Rochester carburetor usage code
- 2738 — carburetor build-date code (e.g., 273rd day of 1968?)
Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.
Content last modified: June 13, 2026 at 10:06 am
Short answer: For a 1969, the way to confirm a numbers-matching engine is that the VIN on the dash matches the partial VIN stamped on the front right-hand face of the block (the partial VIN was also stamped on manual transmission cases and hidden on the body shell). The Engine Unit Number is a separate sequencing number — found on the Protecto-Plate and Chassis Broadcast Copy — with no tie to the VIN, so without the original Protecto-Plate it can’t be verified.
Background:
- 1969 documentation, in order: Chassis Broadcast Copy, Body Broadcast Copy, Car Billing Invoice, Window Sticker, Owner Protecto-Plate.
- The Fisher Body Unit Number is NOT purely sequential — cars were built in batches by many scheduling factors, not order received. It’s on the Broadcast Copies, Protecto-Plate, and Window Sticker. (For 1969, the Body Unit Number and Identification Number were the same.)
- A 3-digit Sequence Number on the Broadcast Copies was used for batch scheduling, with no sequential tie to other numbers.
- The trim-tag date code is the Fisher Body scheduled build date for the bare shell (“Body in White”), not the finished car — the closest finished date is on the invoice.
Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.
Content last modified: June 13, 2026 at 10:06 am
Short answer: The clue is the partial VIN stamp (20P105982): the leading 0 means a 1970 car, and the P means it was built at the Pontiac assembly plant (which was building full-size cars like Catalina/Bonneville that year). For 1970, “YD” indicates a 2-barrel 400, ~290 gross hp from a full-size Pontiac — so this engine isn’t a 1967 Firebird 400.
Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.
Content last modified: June 13, 2026 at 10:06 am
Short answer: The engine build-date code is on the top surface around the distributor hole — a letter plus three digits: the letter is the month (A = Jan, B = Feb, …), the next two digits are the day, and the last digit is the year. Example: B157 = Feb 15, 1967.
Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.
Content last modified: June 13, 2026 at 10:06 am
Short answer: The engine “serial” (Unit) number and the VIN are two different numbers and will never match. But starting in 1968, a partial VIN was also stamped on the block — on the front lower face near the timing cover/harmonic balancer — and that should match your car’s VIN. If it does, it’s the original engine for the car.
- The Engine Unit Number is an internal plant sequencing number (used to match an engine to a specific car). It appears on the Broadcast Sheet and Billing History, with no tie to the VIN — cars with very close VINs can have unit numbers hundreds or thousands apart.
- The block VIN is hard to see — remove the lower radiator hose at the water-pump housing, or use a mirror and light down by the harmonic balancer.
- Engines arrived at final assembly fully assembled, stamped with a two-letter usage/application code (plus a white-and-red label) so the line installed the right parts; the VIN was stamped just before the engine went into the car.
- Service bulletins reference engine unit numbers (e.g., 1967 Ram Air engines: 1st type through unit #646615, 2nd type from #646616).
Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.
Content last modified: June 13, 2026 at 10:06 am
Short answer: A one-digit difference like 205848 vs. 205818 is almost certainly the same number — a weak or partial stamping, not a wrong engine. The Engine Unit Number and partial VIN were hand-stamped (shallower than the code stamp), and the gang-stamp tool could slip during the strike, leaving a “4” looking like a “1.” Given how close they are, it’s the original engine — nothing to lose sleep over.
Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.
Content last modified: June 13, 2026 at 10:06 am
Short answer: The number on the body tag and the VIN won’t match — that’s normal. The VIN is the sequential production number; the body-tag number is the Unit (consecutive build) number. They’re separate systems.
Engine stampings in this example:
- 508743 = Motor (engine) Unit Number
- YJ = 8-cylinder, 326 cid, 250 hp, 9.2:1 compression, 2-barrel carb, automatic transmission
- The “GM4” block casting marking’s meaning isn’t known.
Sources: Firebird Red Book; Catalog of Firebird ID Numbers 1967–93; Pontiac Historic Services; Year One catalog.
Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.
Content last modified: June 13, 2026 at 10:06 am
Content last modified: June 9, 2026 at 7:10 am
