[67see10]

I'm getting ready to buy the parts to rebuild my rear end for my 67 c10 but I am unsure which posi unit to buy.

I want to run a Eaton Posi and 3.73 Richmond Gears but am not sure if it should be a 3 or 4 series carrier.

Eaton Posi Part Number ????
Richmond 3.73 Gears Part Number ????
Richmond Gear Differential Complete Kit 8.875" 12 Bolt part number 83-1018-1