Swapping rear ends???

[Kentuckcard]

Swapping rear ends in my 1981 Regal 455. Pulling out the factory rear(whatever it is), and installing a 8.5 posi out of a GN! Will my driveshaft work, or will I need to find one out of a GN? Have heard different opinions on this.

 

[GNeric]

The 8.5" driveshaft is shorter because the nose of the differential is longer than that of the 7.5". You will need to shorten your driveshaft or use one from a TR or 84 Hurst/Olds or 85-88 Olds 442 since they also have the 8.5". You can even use a measuring tape and hood in on top of the diff and measure down to the pinion seal surface of both housings and see that the 8.5 is longer.

 

[olds443]

use a measuring tape and hood in on top of the diff and measure down to the pinion seal surface of both housings and see that the 8.5 is longer.

That was exactly how I measured mine and had the drifeshaft cut. Just measured the difference and had the welding shop cut,weld and balance it. Came out perfect.
I'm sure with the 455 that you have probably changed trannys too so you will still have to measure it after you get it all in due to variances.
BTW, Post picts when youre done

 

[Kentuckcard]

Just posted a pic in the lounge!