I have a 8.5 10 bolt out of a 74 Nova with 2.73 gears(28 spline axle) that I'm gonna put in my 69 Camaro. I'm going to put a 3.42 in it but all the new gears are for 30 spline axles. Will 30 spline axles fit inside the rearend without any modification? I'm also going to put a posi unit in but the only Eaton I found at Summit was part #ETN-19559-010 and it says that its a 30 spline 8.5 truck 3 series. Is this posi still ok to use for cars?
Thanks.

Will 30 spline axles fit inside the rearend without any modification? I'm also going to put a posi unit in but the only Eaton I found at Summit was part #ETN-19559-010 and it says that its a 30 spline 8.5 truck 3 series. Is this posi still ok to use for cars?
Thanks.
The 30 spline Eaton carrier (19559-010) together with 30 spline axles will fit your housing without any modification.

Eaton also makes a 28 spline posi carrier (Summit # ETN-19557-010) that will fit your Nova housing and allow you to use the Nova 28 spline axles you already have. The same 3.42 ring and pinion will work with both the 19557 and 19559 carriers. The only difference between the two carriers is the axles they use. Both of these carriers will fit your Nova housing perfectly.

Thanks Farm Boy.

These Eaton differentials require special bearings. The standard bearings will not fit. You will need Timken LM102949 and LM 102911 bearings. An 8.5 is an 8.5, whether it is in a truck or car. Even the front 8.5 in the 4X4 trucks from '79 to '87 will work. The internal parts will interchange, except the axles.

Thanks Big Gear Head.

I'm guessing that the pinion yoke is a 28 spline and that I will have to get a 30 spline one correct?

All 8.5 rear ends have a 30 spline pinion shaft and yoke. The axles are where the difference is. They had 28 spline axles up to '89 and then they were upgraded to 30 splines.