Want Spare Alternator-- What to look for at junkyard?

[Wren]

I'm fairly certain that you can swap out the guts of a 55A gasser alternator, but you'll have to add a wire to have the W terminal for the tachometer. The 80/100A alternators are larger in diameter and wont' swap over.

I'm looking into a custom bracket to use a 100A when I get my ride going.