[oldsmo]

hi there, I noticed that every time someone wants to put a posi unit in and keep the the original gears in that everyone recommends new gears right away. Now i agree that new gears and bearings and all would be the best thing to do but some people (like me) just don't want to go through all that. I just put my motor in and for right now I do not feel like gutting the rear. Now hear is the question

I have an 8.5 with 3.73s open unit

I want to put in an eaton unit

Will placing a new posi unit and trying to get the wear pattern back to original place a strain that will brake something or what?

[302 Z28]

There is absolutely nothing wrong with installing a posi unit and keeping the original gears, provided there is not an existing problem with the gears. It should be a relativly easy installation, just keep your shims in proper placement from side to side. You will not have to mess with the pinion so that will remain the same. All you have to worry about is backlash (side to side clearance of the carrier).

Vince

[Crosley]

ditto what Vince said!

[tresi]

Since you mentioned everybody suggesting new bearings also I'll add that will need new side bearings and races as after market posi units use a different bearing than the stock 8.5".