Mike, the 2 sealing rings that you describe on the input shaft seal on the inside of the front pump housing and are for the rear clutch, which is applied in all forward gears but not in reverse. There are 2 rings mounted on the front pump housing that seal to the inside of the front clutch drum which apply the front clutch in direct, O/D, and reverse. In reverse, the front clutch and the rear band is applied.

You should be able to check both clutches sealing rings and both drums piston seals by air checking the front pump and drum assembly on the bench.