69volunteer 84 Report post Posted July 13, 2022 I have posted here a few times regarding swapping the rear end out of my fastback. A friend gave me a brand new 3:55 Ford Performance R&P for an 8.8 inch rear end. He ordered it for a late model f150 and did not install. A quick search based on various part numbers looks like this will not work for me. What would have changed over the years? I know the length of axles changed for various applications but what internally would have changed? Quote Share this post Link to post Share on other sites
Midlife 814 Report post Posted July 14, 2022 The 8.8 rear end is an entirely different design than the vintage Ford rear that came with first generation Mustangs. I believe the 8.8 was introduced sometime in the late 70's or early 80's. It is not at all compatible with the earlier 8" or 9" design. 1 det0326 reacted to this Quote Share this post Link to post Share on other sites
TexasEd 188 Report post Posted July 15, 2022 Yep 8" vs 8.8" . they are not the same differential. Quote Share this post Link to post Share on other sites
69volunteer 84 Report post Posted July 15, 2022 ahh...ok, got it. I was thinking they were the same. Thanks Quote Share this post Link to post Share on other sites
EastYorkStang 63 Report post Posted July 25, 2022 One loads in from the front as an assembly. The 8.8 has all the guts inside. Quote Share this post Link to post Share on other sites
