I've got a Ford rear end (car) in one of my trucks and was trying to decide what to do.
Check these dudes out
http://www.rottenleonard.com/Menu.html
It's a drill guide that you bolt up to your current bolt pattern and drills a new set of holes as you re-position the guide around to each of the studs. Bang out the old studs and in with new pattern wheel studs, and boom. New pattern.
here's the whole chart of what you can adapt to and from:
http://www.rottenleonard.com/Drill-guide-price.html