Those codes are the same for '62, there also codes MT and MU that are 4.11. the '64 diff would be a Salisbury type, no 3rd member. The housing is 1 peice. For '64 the gear codes are;
WA,WC,WE,WG,WJ-3.73;WB,WF-3.07;WD,WH-4.11. I have been told that some parts will interchange with the earlier diff, but i have yet to confirm this, one day i'm giong to check a Hollander manual on that. 1 note-the '63/64/early'65 12 bolt diff has 17 spline axles,they can be converted by swapping to the 30 spline axle if you want to add a traction aid. There are no 17 spline traction aids for the 17 spline diff.
