What you have is what is known as an Eaton "corporate" rear end with the drop out center section. I believe it was referred to as a H033. It was common to 1/2 ton trucks from 55 through 62. There isn't much available except an aftermarket 3.36:1 gear set.
I don't believe there was a posi available for that unit, but if there was it would have been extremely rare. There are many 10 bolt rear ends in both cars and trucks in later models but it's unlikely that any of the internal components interchange.
Fred
Note: The spare axle(s) I have for my 56 have 17 splines.
Last edited by rfs56trk; 12/08/2020 10:29 PM.
