You can make bushings/adapters to use the late model wheels on the 51 truck. The new wheels have a nominal 5.25" center hole, and the old ones a 4.75" center hole.
If the 55 axles are in decent shape and priced right, then I think a complete axle swap would be a better choice. Assuming that they are early 55 axles, and are a bolt in swap for a 51? Or if they are late 55 they may still be suitable and bolt in???
Or perhaps the hubs and even brakes can be swapped from the new axle back to the old one?
Simpler yet may be to forget about the 55 stuff and search for the readily available 48-53 two or three piece lock ring wheels with the correct center hole already.
So many choices,
Grigg
