I've been offline, myself. Busy, as I'm sure you are.

The two drums miked the same in all measurements that I could accurately pull, except for that step in. Aside from one being lipless, of course.

The gentleman who runs the transmission shop I bought it from sent me a new snap ring and an old plastic style (Torlone?) washer. I used the new metal washer with the relief cuts (relief cuts placed toward reverse drum).

He also pulled measurements from a half dozen drums for me and sent me the drum with the largest cup. He said that .075 was the most common he found, aside from the .088 he sent me.

It installed with almost no play, but the snap ring sits firmly in the groove and will move rotate around the groove with a fair amount of force applied. I figure this means that it's seated properly, and is not binding at all.