Looking for answers

[SHORTDOG99]

Hey guys, I picked up a 5 lug 12 bolt Chevy rear end with posi and the guy i got it from said it was out of a 67 C10.

But if it was, shouldn't it have been a 6 lug?

I started to clean it up and came across some numbers, maybe you guys can help me out with this. Standing in place of the driveshaft looking at the rear end just to the right of the pumpkin (drivers side) i found a GM63 and in the same place but on the left side (passenger side) i found the numbers 3896838 N
and then further left on the actual axle tube i found some numbers stamped into the tube that read RHB (which looks to be stamped over an "RF") then W356 2 E (which would be the number to go by? the "RHB" or the "RF"?) so can anybody decode this and tell me what year / model this rear is out of so i know what brake parts to look for? I am pretty sure it has either 3:07 or 3:08 gears. Thanks for your help guys!