My Dana 70HD came from an 80's P30 motor home chassis and if I remember correctly I moved the spring pads 1" each to the outside.
Helped a friend with a Dana 80 for his 53 GMC 2 ton and it lined up perfectly, spring pads were already the right width. We never could figure out what the axle came from but my best guess is an Oshkosh step van, it had 6 lug Budd wheels.