An even dumber answer. I wrote down the numbers when I fitted the replacement rear unit but have lost them! Short of pulling the front cover off the diff and MAYBE seeing them with a mirror I am stuffed.
That number I put up is there OK. I will follow up tracking it to see if something more modern had it (I am pretty sure they did). The main problem is they changed everything in about 1942 from 2 pinion to 4 pinion. I don't know if that bears on the crown wheel and pinion gears. If the Crown wheel is still 8 3/4 it well could fit OK. The mounting bolts increased in size but that is not impossible to correct.