No, there are some slight differences, early 89-90 cases have slightly smaller (thinner)
gears, and is why the 4.24 gears do not fit into the case. The real difference is the
front cover, not the body of the case, but you might as well swap the whole case
There is also a version that has a different output spline count, some are 26 and some
are like 12 or 16, and have a square shape to the spline, like an American made spline
on a full size truck
Other than that, the gear ratios are the same, and the cases will interchange, but if
you want the lower gears or don't get the driveshaft from the lower spline count donor
you might have issues later
Wild