[drathaar907]

Allright it is confirmed (talked to a few local diff guys) My chunk is junk! from spinning inside my case (pinion grinding on it) They also advised not to try this project by myself (replace gears rebuild etc.) Local guy is coming out to my house once all parts accumulated. Brings me to this question: Posi or non-posi? Diff guy here says if your not going to drag etc. posi not needed, says car will skip/hop doing corners etc. He recommened going non-posi and a 3.73 gear. Your guys thoughts?? Also have found a part number #3869788 it is a regular non-posi spider gear diff set, guy says it is for a series 2 12 bolt carrier. I believe I have a series 3 (non-posi stock 3.31 1967) are these parts compatible??? Add said it would take a gear spacer??? to fit gears - not sure what that meant?? will ask. Input appreciated

 

[big gear head]

If this is a performance car then it needs a posi. Even if you don't race it you will get better traction with the posi. If the posi is set up properly then you will not even notice it durring normal driving. The Eaton posi is the best that I know of for GM cars that are street driven. As for the other differential, pass on it. You do NOT want to use a spacer if you can help it.

When this guy shows up to install your gears be sure that he knows how to set the pinion depth, backlash and bearing preload. There are a LOT of people out there who think they know how to install a set of gears. Most of them are dealership mechanics who just take out one set and stick the others in without shimming anything. You do not want that kind of installation.

 

[JJ'65]

Hmmm. Says posi not needed. True; but posi is quite useful if you live where it snows once in a while; unless you like to get stuck or deal with chains. Says skip-hop doing corners? Not the Eaton in my '65. GM wouldn't sell something like that. It is true that the stock Eaton posi in my '65 started grabbing sometimes when making a sharp left turn from a stop sign. But that was after 90,000 miles. Drained rear axle lube and refilled with Sta-Lube GL-5 90 weight cured that. I'd be sceptical whether someone who provides this kind of disinformation could setup properly a rear gear set.

My $0.02