hello.im looking to upgrade my gears and hope to get some advise.i drive a 85 irocz28.305 tpi 700r4.all stock.i currently been offered a complete rearend froma 95 z28.its a posi with 3.42 gears and disc brakes.i currently have the 3.23 non posi disc rearend and wanted to know if only the posi unit itself from the 95 will fit into my differential housing? because i hear the complete rearend will be slighty longer than the stock one.any answers are appreciated.thanks!

 

No, it wont work. Your '85 has 26 spline axles and the '95 has 28 spline axles. The differential in the '95 will be an Auburn. You can upgrade yours by using a set of '90 to '92 axles, but I wouldn't bother installing a use Auburn. A new Eaton Posi, Yukon Dura Grip or a Eaton Truetrac would be good. If you do the 28 spline upgrade the a used Torsen from a '98 to '02 would be good.