Need help with rear end

[Brandon770]

So here is the deal I have a 2wd 1967 Gmc stepside long bed. Now this truck I believe has a 10 bolt dana 44 spicer rear. The ring gear has gone out of it. It is a straight six with the 3 speed w/ granny gear as well. Total 4 speed just so there is no confusion. Now the problem I am having is I just can not find parts for this at all. Every were I have looked says they do not fit my model of truck. Can any one tell me were to find a total rebuild kit, Pinion gear and u joints for this rear end. Any help would be great. Thank you.