One huge difference between 60s and 14-bolts is that there is great variation among 60s whereas the 14-bolt has had only one minor change. According to Drive Train Industries' (DTI) Tony Cosslett, the 14-bolt's inner pinion bearing, bearing cage, and crush sleeve were upgraded in 1988. That's it. The housing and other internals were unchanged. On the other hand, Dana made three basic versions of the full-float 60. The most common 60 has 30-spline axleshafts that are 1 5/16 inches in diameter. Heavy-duty 60s with 35-spline, 1 1/2-inch axles are rare in stock 4x4s. Some late-'60s Dodge 4x4s and late-'60s to mid-'70s Ford 4x2s have 16-spline, 1 5/16-inch 60s. Dana made many different variations of the 1 5/16, 30-spline 60 for Dodge, Ford, GM, IHC and Jeep. Many parts don't interchange, so 60s are generally more complicated to shop for and build than 14-bolts.