[69]

Hey Guy's,
I'm getting an Eaton diff. for my Olds 8.5 10 bolt, I'm going from a limited slip 2.73 to a posi 3.73 for around $900 installed....Compared to a 12 bolt posi for around $2000 I think I'm sticking to a strong 10 bolt.
What kind of performance will I notice by going with this size gear, also what's your opinion on gear size, higher or lower?
Btw, The car wont be driven too much on the freeway, I just want to get some respect on the street and the strip.
Specs on the engine;
355 mild built
750 carb
500/500 lift cam
2000 stall
3 speed auto trans
Thanks

[badazzbowties]

sounds like a plan to me, im doing the same with my 10 bolt well Ill tell you the difference will be night and day especially with the engine combo you have, good luck keppin a fresh pair of tires on her!

[georgia 69]

I agree with the combo you have it should be a great running car,you will notice a HUGE difference from idle throughout the power band,it should be fun to drive.What size rear tires do you have?

[ENP]

I went from a 10-bolt 2.73 peg leg to a 12-bolt 3.73 eaton posi unit behind a TH350. Driving down the highway sucked. I now sport a 700R4 and I cruise at any speed down the highway. Before anybody gets into an up roar this is my personal experience. My friend had a 502HO(I know its not your set up) in his 70 chevelle with TH400. The motor had a cam change and the heads were ported, instead of the factory 8.5:1 compression it's now just over 9.1. He tried a 4.11 w/ 3000 stall and a 3.08 and a 2000 stall. He ran 12.13 with both set ups on 17" street tires. I don't know how much torque you have in your motor but I would consider going with a 3.55-3.08 gear if you don't plan on going with an OD tranny. Just my .02 cents.

[DOUG G]

I did this very swap in my 68 with an 8.2" 10 bolt.

Best with 2.73 posi was 13.51@101.7 (great traction)
Best with 3.73 posi was 13.2X@103.X (next to no traction)

With traction I think it would have been a 13.0 easy. So I'll say you should see about .5 faster if you can find traction.

[69]

I have stock 14" tires now but future plans is to give this car a pro touring look.... I was thinking that the 3.73 was a bit much and maybe go with the 3.55 but I'm sticking with the "go big" method.
Thanks for the input, I'll get you that holeshot video ASAP! (In a controlled environment of course)

[arocars]

I'd suggest 3.55:1 gears.