I did my TR-4 many years ago by using a delco mid 70's 37 amp altenator. Used an unknown tension bracket. Using crimp connectors,wired everything through original regulator an ammeter. The generator pully fits great with a little grinding on the fins. The 37 amp runs everthing great and won't overload the wiring. GM also had a 32 amp but it's hard to come by.