If material compatability is not the issue, you'll need to check a few other things. Is the dist. shaft straight and free to rotate easily? Check the height of the gear relative to the boss on the housing where the dist. is bolted to the intake. Is the dist. hole in the intake centered over the
oil pump drive rod or is it off center causing a side load? I've seen MSD billet dist's that didn't have the hexagonal
oil pump drive rod hole broached deep enough into the shaft of the distributor. The dist. bottoms out on the
oil pump rod before the housing rests on the intake. A difference of .050" and the oil pump becomes heavily preloaded by the distributor, becomes very hard to turn, and the distributor gear wears out in no time. A close inspection of the wasted parts is your best clue what went wrong in the first place.