Help ID my rear end?

[neirfin]

I was expecting a different configuration on my 69 C20, my rear drum comes off without the hub attached, I also am seeing a different set of retaining nut... I was planning on having to remove the hub to service the drums, full replace down the cylinder... do I still have to remove hub since the drum comes off without the hub? These are the only markings on the rear end I could find, no mention of HD rear on the glove box paper slip...

Thanks