New cradles if you don't have the ones for the 4" tubes on the 80. And I would go with new u-bolts too to match up larger diameter and the old ones have been stretched as well.
You might want to think about upgrading to a 1480 yoke and pinion on the rear while you are at it. Spicer makes a no-zerk u-joint that will hold up much better. This all depends upon what you're going to do with the truck. If pulling - go with the 1480.
Search for dana 80 parts on here, there is a list of part numbers for the u-joint and yolks.