[Captainfab]

Assuming that the truck inquestion is the '71 in your sig, a '88-'98 differential (8.5" 10 bolt) is going to be aprox 1.25-1.50" wider than the original 12 bolt that came in your truck. A '99+ differential is going to be aprox 4" wider.

I currently have 3 different rear disc conversion brackets for the '64-'87 truck differentials with the 5x5 wheel stud pattern. Links in my sig \/ \/ \/