My '68 has fairly legible white letters (H6X) on the bottom of the axle housing and very faint yellow letters (-DS8?) on the back.
From another thread related to the markings on the bottom
"1- The markings on the bottom of the housing (directly below where the 3rd member would mount) are normally seen in white or a yellow. Most of the time these are destroyed by the elements or by floor jacks. Letters are large, applied with what looks like a 1/2" brush and are fairly sloppy. No real pattern as they can include numbers and letters or what looks to be all letters. On many of the housings we see (white or yellow also) a two digit what may be a letter and number on the rear face (back side of where the third member attaches), Not allot of examples so no pattern can be defined at this time "
Believe this was coding for workers inside the Sterling plant. Have not discovered a relationship to gearing or application so far.
As for the possible badly applied DSO to the back side of the housing I've seen/found is a handful of times on 68 Shelby's but not many
One of the multiple threads on the site on similar or related subject.
https://www.concoursmustang.com/forum/index.php?topic=18238.msg115635#msg115635Any suggestions on how better to expose the letters on the back of housing without making them disappear and what the letters mean? Thanks Chris
Best nondestructive effort I've found is a number of good clear pictures then using something like Photo Shop to adjust the contrast up an down the scale to pick of those slight differences will sometimes produce positive results
