Frank,
There used to be adapters made for changing bolt patterns, but they are NOT recommended for use on the rearend except for emergency use (spare tire). They also make the rearend wider.
As for the '58 rearend, re-drilling the axles and drums might be your best option. Just make sure that the parts are in good condition, or you will be doing it twice. Brake drums from a 51-65 1/2 ton 2WD no posi could be substituted for the 5 lug drums, after you get the axles re-drilled. Car and truck axles are not interchangeable.
They show Euro streetrod stuff in Street Rodder magazine from time to time. Seems like there's alot in Britain and Sweden. Perhaps you need to put out some "Wanted" adds in local papers, websites, etc... to scrounge up what you need.
What about Euro made cars/trucks? perhaps looking outside of the "big three" would get some results your looking for. Just a thought.
Seems to me late model Jeep models have 6 lugs, some Dodge trucks also. Not sure if the pattern is the same, but maybe you can find something like that to work with.
