Ok this weekend i took in a 1983 z28 that had 373 rear end in it ok ,the read end is no good but im shore the gears are i would like to take the posi unt out of a 1992 rearend that has 273 in it.Take the big gear of the old rear end witch would be the 373 rear and put them on the posi unit and just put it bad in place would this work out with out problems and if not why

 

No, won't work. But it can be made to.

You'll need a ring gear spacer, because the carrier (posi) for a 2,73 gear, locates the ring gear about .400" farther away from the centerline of the pinion, than the 3.73 gears require.

You'll also need to use the axles out of the 92.... the 83 axles have 26 splines, but the 92 carrier has 28 splines, and those axles will just spin in the carrier. Put in new axle bearings while you're at it.

Re-use the old rear's carrier shims. The shims don't shim the carrier; rather, carriers are all the same, but housings are different, so the shims actually shim the housing to fit a carrier. So keep the shims with the housing they came with, in the places they came, and if the ring gear spacer you get is the right thickness, it'll all just go back together right. Check the backlash with a dial indicator just to be sure.

 

You should also check contact pattern, just my 2 cents.

 

well here what im doing i have a 1992 rear with 273 in it posi and the one in my car is a 373 nonposi i would like to keep the 373s but the rear end in the car is about to blow how much of a diffrence am i looking at if i leave the 273 in the posi and drive it like that .This rear end sits behide a 305 motor and a t 5 tranny

 

why would i sapce the ring gear i though you would be shimming the the pioin gear what is the diffrence and do you know where i can find pics

 

The ring gear on a 2.73 set is different than the ring gear on a 3.73 set. You have to use a spacer on the 3.73 set to get the pinion and ring gear to work together.

No offense, but this sounds like something that is over your head. Take it to a professional. Setting up rear ends requires special tools and knowledge that we common folk dont have.