Well first of all I don’t know how to spell it…

What years did Chevy make Posi rear ends? And what models are they typically found in?

I Want to convert my 66 3/4 ton to a 5 or 6 lug posi rear-end. Right now it has a 8 lug posi 4:10 but I want to get more speed out of it and get a 6-5 lug bolt pattern.

Thanks for any advice.