Here’s how you can tell them apart. Left to right, front row: Salisbury 2HA, Salisbury 4HA (actually Dana/Spicer 44, but looks and acts the same) Back row is a 4HA Powr Lok. The 2HA differential is very distinctive in that the ring gear bolts thread through a threaded flange on the inside diameter of the ring gear, instead of directly into the back of the toothed part of the gear as is done on the 4HA (and virtually all differential units, save for Toyota).
