1968 trans/rear combo

[John B.]

The 4 speed transmission in my 68 is coded P8A04 with vin 18W267305. The input shaft has 2 grooves on it which suggests it is a M20. I know the trans is not correct for my October build 68 vette. Should a 68 L36 vette with a 3.55 AZ coded rear have a M20 or a M21?

Thanks,

John Brough

[Ralph S.]

Re: 1968 trans/rear combo

The VIN 18W is from a 1968 Nova built at Willow Run MI.

[Wayne M.]

Re: 1968 trans/rear combo

The 4 speed transmission in my 68 is coded P8A04 with vin 18W267305. The input shaft has 2 grooves on it which suggests it is a M20. ...... Should a 68 L36 Vette with a 3.55 AZ coded rear have a M20 or a M21? ..

John -- from an old NCRS Pocket Spec Guide that I have, your car with a correctly dated AZ code rear would have originally had a close ratio 4-speed. The 3.55 was considered "performance" ratio for the L36 with M21; 3.70 ratio was also available with the M21, and called "special purpose" ratio.

[Joe L.]

Re: 1968 trans/rear combo

The 4 speed transmission in my 68 is coded P8A04 with vin 18W267305. The input shaft has 2 grooves on it which suggests it is a M20. I know the trans is not correct for my October build 68 vette. Should a 68 L36 vette with a 3.55 AZ coded rear have a M20 or a M21?

Thanks,

John Brough

John-----


While a 1968 with L-36 and 3.55:1 ratio rear gear would have originally been equipped with an M-21, an M-20 will work very nicely with that combination.