Rockauto shows several flavors in stock. No telling on shipping, however.
He should also try unplugging/replugging, twisting, or pressing against the small connector. Sometimes the circuit connections can get intermittent.
Probably a longshot, but it will only take a few minutes, and it's free.
The only alternator I have for an 88 is a core, and it's for a Duke, anyway. (Lug placement is different.) Sorry.