Need help identifying this rear axle...

[Gypsyman]

I've been browsing for a disc brake front and rear set-ups to swap into a '63 C60 that I brought home and I ran across an odd combination that I don't seem to be able to identify.

The seller claims that both the front and the rear came from a mid 1980's GMC P35. Possibly an old Matco truck. Lug pattern is the standard 5 front - 10 rear that you would expect. The front looks like a regular step van A-arm setup but the rear is not what I'm use to seeing in this application. It a HD, front drop out, square tube axle like my small Internationals have. I'm hoping that the tubes are stamped with some kind of identification but I haven't been able to see the items in person yet.

The center chunk has the following markings...

JES3891
5 43

That's about all that's legible. I'm assuming this indicates a 5.43 gear ratio but I can't find anything regarding the JSE3891 marking.

Richard

[Robert1970C20rstbukt]

Looks like a Rockwell C100 axle, I did a brake job on a 1990 HD 3500 with that axle and the pads were the same for the front and rear, brake code was JF9. It had an ID tag on the axle tube somewhere from what I remember.