What GM plant installed my Corvette drive train assembly?

[George H.]

[Joe L.]

Re: What GM plant installed my Corvette drive train assembly?

The engine block in my 1973 LS4 Corvette, 3999289, was cast 06/11/73 in Tonawanda (F11-73). The Muncie M21 4-speed transmission, 3925661, is date coded 06/14/73 (P3H14B). The engine assembly date is stamped T0619CWM, 06/19/73. The differential is stamped AXW176E2, 06/25/73. The Trim Tag for the build date is 07/06/73 (L06).

Question. Did the Tonawanda plant install the pressure plate and clutch assembly on the LS4 engine and install the transmission before shipping it to St. Louis, or, was the transmission shipped from Muncie Indiana to St. Louis and one or more of the St. Louis assembly stations did the drive train transmission assembly, including the differential, before dropping the body on.?

I can’t find any article or history addressing that question.

George Hunt
C/3 1973 Coupe LS4 M21 4-speed. Metallic Yellow
Florida Chapter NCRS

George-----

Flywheel, clutch disc, pressure plate and bellhousing were installed at Tonawanda. Transmission was shipped from Muncie, IN plant to St. Louis and installed at St. Louis.

[George H.]

Re: What GM plant installed my Corvette drive train assembly?

Appears you know just about everything about Corvettes Joe. I assumed Tonawanda did the clutch assembly and bellhousing but not sure about the transmission. With the engine stamped CWM, the plant knew the engine was assembled for a 454 manual shift car. I believe a 3-speed manual was standard in '73 and the 4-speed was optional, either wide or close ratio. Mine is a Muncie close ratio 4-speed. Are all LS4s with M21 transmissions close ratio? The production records I have indicate that 12,537 '73s had a manual transmission. There were only 3,704 Coups with the LS4 engine and 714 convertibles with the LS4 sold with a M21 close ratio. It appears a lot of 1973 Corvettes had the 3-speed manual.

Thanks for the clarification Joe.

[Joe L.]

Re: What GM plant installed my Corvette drive train assembly?

Appears you know just about everything about Corvettes Joe. I assumed Tonawanda did the clutch assembly and bellhousing but not sure about the transmission. With the engine stamped CWM, the plant knew the engine was assembled for a 454 manual shift car. I believe a 3-speed manual was standard in '73 and the 4-speed was optional, either wide or close ratio. Mine is a Muncie close ratio 4-speed. Are all LS4s with M21 transmissions close ratio? The production records I have indicate that 12,537 '73s had a manual transmission. There were only 3,704 Coups with the LS4 engine and 714 convertibles with the LS4 sold with a M21 close ratio. It appears a lot of 1973 Corvettes had the 3-speed manual.

Thanks for the clarification Joe.

George-----


No 1973 Corvettes were ever equipped with a 3 speed manual transmission. The last use of a 3 speed manual transmission in a Corvette was 1969. Beginning with 1970, the 4 speed was the standard transmission for a Corvette as was posi-traction. The 1973 LS4 was available with either a close or wide ratio 4 speed transmission. It was also, of course, available with a THM-400 automatic transmission. Any of these transmission choices for 1973 was a no cost option. Rear ratio choices depended upon the transmission chosen.

[Mark F.]

Re: What GM plant installed my Corvette drive train assembly?

...I can’t find any article or history addressing that question...

At least 6 years behind yours, but here’s John Hinckley's C2 Assembly Process Presentation (available in the Database of Restoration Documents [DoRD] Sticky Post):

https://www.forums.ncrs.org/attachme...3&d=1499375207

That took place at the 2nd station on the Engine Dress Line.

[George H.]

Re: What GM plant installed my Corvette drive train assembly?

Love it when I get educated about early model Corvettes. Thanks for the link Mark.