Popular mistake "I have a (fill in engine details), and I discovered that the damper ID and pulley alignment of a (fill in very different engine) is the same, so I bought one". My favorite: "I can't afford a good one for my 235" stovebolt (long, fragile, 4 main bearing, long stroke L6 crank) but the 283" V8 (short, rigid V8 crank) damper fits, so I installed it Tuesday - and so far it's great!".
GM made over 30 different SBC dampers, and none of them are used on any other engine.