the 4.11 may not be listed, because it was not a separate option but paired with the OD 3 speed trans, which was available from 55.2 on .... '58 was the beginning of a variety of optional rear offerings, and AFAIK the first year for the posi, but the 3.9 was still "standard" and any of the others would be a rare find nowadays, I've searched for years but never found a posi and the only 3.38 gears I've seen were NORS at a rear end specialty shop or the the current new production from Patrick
Bill
I got one, but its more of a limited slip,has some clutch plates backing the differential side gears kinda like where the thrust bearings are. And its in an old style rear axle, like the 57's had. Hmm I guess that is what 58's used, 59 has a newer spread case design.
