1966 Positraction

[Craig C.]

For 1966, was G81 Positraction Rear Axle option available for base engine 300 HP cars with M35 Powerglide Transmission?

[mike cobine]

Re: 1966 Positraction

According to the NCRS Spec Guide, yes.

The 3.36 was standard and was available as Positraction as an option. The other optional gear was 3.08 and only as Positraction.

[mike cobine]

Re: 1966 Positraction - Oops,

I read too fast and wrote before thinking. The 3.08 Positraction is listed only with the 2.52 four speed on the base engine.

[Joe L.]

Re: 1966 Positraction

Craig------

G-81 positraction was available for ANY rear ratio. Of course, there were only certain ratios available for a given powertrain combination. Also, some ratios for any given powertrain were ONLY available with positraction. However, there was no case in which one could ONLY get a non-posi. This wasn't just true for 1966. It was pretty much the case across the board for 63+ Corvettes. If there were any exceptions to this rule, I can't think of one.

[Duke W.]

Re: 1966 Positraction

In the simplest terms the only available axle ratio for 300HP/PG was 3.36 - no optional ratios, but the standard open differential 3.36 could be upgraded to positraction by specifying G-81.

Duke

[Craig C.]

Re: 1966 Positraction

If the 300HP/PG standard 3.36 was upgraded to positraction, is the axle code still AK ?

[Joe L.]

Re: 1966 Positraction

Craig----

No, it would then be "AM".

[Craig C.]

Re: 1966 Positraction

Thanks Joe, does "AM" apply to powerglide also though?

[Joe L.]

Re: 1966 Positraction

Craig------

Regardless of what some references might imply or say, as far as I know, the "AM" coding was used for any non-HD (i.e. big block) 3.36:1 positraction axle. If it was not used for positraction with Pwerglide, then what coding would have been used?

There is absolutely no reason why a 3.36:1 differential needed to be any different for 4 speed equipped cars and Powerglide equipped cars.

If you look at a lot of the "charts" and take them literally, then one would have to conclude that some cars with automatic transmissions used no differential, at all. Consider that for 1967, there is NO code specifically shown for ANY rear differential used for an L-36 with Powerglide; ALL the 427 codes in many of the charts show nothing but codes for 4 speed cars.