Differential Confusion

[72 Cheyenne K20]

I went to NAPA today to try and find a replacement for my Free/Lock hub knob on my 72' 3/4 ton. I don't think the guy has laughed that hard in a long time. Anyway, I started talking to him about different diffs for front and rear. I haven't really thought to much about them yet but wanted to ask what the options were. I have a d44 in front and non posi 10 bolt in back. I looked at some posts today and I saw one that said that 10 bolt rears were not introduced until the mid 80's. Is this true?I also wanted to ask any preformance differences between d44 & d60 for the front and 10 bolt, 12 bolt, 14 bolt for the rear?

Thanks, Scott