Rear End Possibilities (Ratios)

[Ken K.]

On a 1966 327/350hp car what ratio rear ends where available? This list of ratios should be different for the M20 ,M21, and Powerglides transmissions.
For example: Was a 3.55 Posi rear end available for all three trannys?
Thanks

[Joe L.]

Re: Rear End Possibilities (Ratios)

Ken-----

Rear end ratios for 1966 (and most other years, too) depended on engine and transmission. For any given combination of engine and transmission there was a standard ratio and, sometimes, 1 or more optional ratios.

For small blocks, the standard rear ratio was available with or without positraction. However, all optioal ratios required that positraction be also ordered. All big blocks required the positraction option regardless of rear ratio.

For 1966, 3.55:1 was available only as an optional ratio for L-79 with wide ratio 4 speed (M-20) as well as the standard ratio for L-72 with close ratio 4 speed (M-21).

For 1966 L-79 with wide ratio 4 speed (M-20), the standard ratio was 3.36:1 and the only optional ratio with this combination was the 3.55:1 that I already mentioned.

For 1966 L-79 with close ratio 4 speed (M-21), the standard ratio was 3.70:1 and the only optional ratio was 4.11:1.

Powerglide was not available with L-79, so that issue is moot.

[Joe R.]

Re: Rear End Possibilities (Ratios)

Hi Joe:

I have a 67 327/300 with Powerglide. I think I read somewhere that the only ratios offered with that combination were the standard 3:36 and an optional 3:08. Do you know if that is correct?

[Joe L.]

Re: Rear End Possibilities (Ratios)

Joe-----

For 1967 base engine with Powerglide, only the 3.36:1 ratio was available. There were no optional ratios. However, the standard ratio differential could be ordered with positraction.

[Joe R.]

Thanks Joe! *NM*