[Captainfab]

I would imagine there is a place to look up the build code on that differential, but I have no idea where to look for something that new. It sounds as though all you want to know that you don't already, is the year? If so, just pull the cover and look at the year stamped on the ring gear.

I don't think the pinion angle will be an issue but the width of this differential could be. Typically full size van differential are 3-4" wider than a pickup differential. This may or may not be an issue with your '70 C30 C&C. It will depend on what you plan to use for a bed on the truck.