I have a 1981 Sapporo, and I just upgraded the alternator from the original 50 amp to a 75 amp.
Source, 1986 Starion, with intercooler, before May 1986.
They switched the plug halfway through 1986. The early one has the T-shaped plug, so it fit perfectly.
I think it was originally made by Bosch.
Part numbers from various remanufacturers.
BECK/ARNLEY Part # 1860730 << the one I used
BBB PRECISON Part # 14445
REMY Part # 14885
ACDELCO Part # 3341628
If you have the other plug, you need this one.
ACDELCO Part # 3341622