Fast66vette

Im currently running 3:70's but I want to run 3:36 or 3:08. I have a big block with a m20. Anyone running this rear with a bb and how much of a diff are the two rear ends in performance? How much of an rpm drop between them?

larrywalk

The rpm drop will be 1-(3.36/3.70), or about 9%.
With 3.08s, the drop will be 1-(3.08/3.70), or about 17%.

thomaswat

I just replaced my 3:08 with a 3:70 so I have the ring gear and pinion for sale if you have an interest. They are in great shape, no noise. Came out of my '65 vert.
Tom

Rayfry

How much for the ring and pinion?

DIP51

Or you could put a TKO-600 in front of the 3.70's!!!!

I did that on my '71 about 8 years ago. Man, it was a BLAST to drive!!!!! Absolutely a Raped Ape out of the hole and cruise the interstate at 75mph turning 2200rpm!!!

Kinda miss that car...it went to Australia about a year ago.

biggd

I wish you were closer to me. We could swap complete center sections. I have 308's in my 67 with a T56 6 speed.
I have to be going 85 to even get to 6th gear. I agree with some others here, put a 5sp in it and you will never look back.

thomaswat

I have a Tremek 5spd and couldn't stand the 3:08. That's why I changed to the 3:70...major improvement. The Tremek has a .64 fifth gear ratio. With the 3:08 fifth gear was almost useless at less than 85 mph.

thomaswat

$125.00 plus shipping. They are G.M. gears

Frankie the Fink

That is what is in my otherwise stock '61 - great combo. I'm thinking a 3.08 will be a dog off the line...

The OP will have to change his screen name from Fast66vette to Fido66vette...