You should replace the axle seals for sure. The pumpkin is quite heavy so it can be tricky to get lined up. The thin paper gasket can distort really easily so be careful with it. I would suggest getting new metal axle flange gaskets. FLAPS should have all the gaskets. Here is an article on the subject:
Pumpkin Swap


1951 GMC 1 Ton Flatbed -- It is finally on the road and what a great time I have driving it!
1951 1 Ton Completed


My Chevy Master 4 Door is on the Road!