Original Alternator is Paris Rhone 60A externally regulated: If the diode bridge fails diodes can be replaced with ½ inch diodes from Delco 10DN alternator, 25 to 35 amp each (three positive and three negative diodes). The heat sink is very brittle and will crack if not properly supported when pressing the diodes in/out.
Optional alternators include:
Delco CS121 Alternator from e.g. 1989-93 Pontiac LeMans 1.6L (Delco 321426; Lester 7929). Delco CS121 Lester 8215 (Used on 91-97 Saturn) or 8217 (1994-95 Camaro).
The Saturn/Camaro alternator has better clocking of the adjustment bracket than the LeMans alternator and therefore will not require an extension for the adjustment bracket, but the mounting feet are short and therefore the fan will rub on the accessory tray unless modified. The LeMans alternator can be mounted without modification to the accessory tray if the front mounting hole is first elongated downward until it is an ellipse with a 9mm major axis and then drilled to 9mm diameter.