First appearing in 1977, the 8.8 Ford ... have axles that are the same length side to side. The '86'93 Mustangs have 29.063-inch axles, and the rearend is 59.25 inches from axle flange to axle ...

Beyond that, the heavier Dana 60 is a likely hardcore upgrade path, but swaps over to an 8-lug wheel pattern on factory axle flanges. Aftermarket support for the Ford 8.8 axle is substantial ...