On the left is the ring gear on the right is the pinion gear. These are the parts that make up a final drive. So since he has the pinion gear for the 5.0 all he need is to make the correct ring gear to bolt up to the VLS and its over.
So this means if you can ship him your ring gear from a VLSd he cam make all the measure ments and game over. Then he could make any VLSD final drive after that.