Check the exciter wire on top of the alternator, make sure it's making good contact.
If it's not a wiring issue, then it might just be a poor quality rebuild that had an assembly flaw. See if you can get it exchanged.
__________________ 1998 Camaro Z28 | 1971 Nova SS-350 Previous LSx Vehicles:
2002 Camaro Z28 | 2000 Trans Am WS6 | 1999 Camaro Z28