I've put 3 alternators on an '86 Cutlass Supreme with a 307, and none of them will charge. Battery voltage at alternator BAT post while running, and full-field testing reveals no change. Charge light only comes on when the R's are above about 2000, but the battery runs down even at idle. Anyone seen this before? I sure haven't. My boss is experiencing similar problems with his '80s El Camino, so maybe it's more common than I thought?