1987 to 1989 water pump changeover?

[cawcislo]

there are different common block or newer style pumps. I think the early common blocks 89, 90 or so had a smaller diameter bolt pattern on the pulley and later common blocks had a larger diamter bolt pattern on the pulley. When I went form my 87 to 89 common block t2 and changed to new style pump I needed the pump, housing, alternator bracket and I had to open up the hole in the alternator a little bit to accept the bolt for it to bolt up to the bracket.