62' c10 with a 72' c10 rear axle. Driveshaft problems

[Triple6Goat]

I have a 62' chevy c10 short bed that I swapped a 72' c10 rear axle into so I could have 5 lugs and do a disc brake conversion. I got new trailing arm saddles welded on so that it will bolt into the truck. The problem I have is I think the U-joint from the 62' driveshaft is to small for the 72' pinion. Does anyone know if a pinion from a 62' axle will fit on a 72' axle or a 72' drive shaft fit in a 62' 3spd. trans?
I would pull the pinion off my old rearend and see if it will fit the 72' axle but I sold my old axle already.