Well, here's the story. It's the reverse/low band (at least on the K4A/K4C trannies, I suspect it's still a band on the 722.x trannies) that wears the most.
A three speed has four clutches/bands (different builders use different combinations, and GM 350 hydramatics have TWO second gear actuators, one a clutch, the other a band) -- forward clutch, direct clutch, 2nd gear clutch or band, and low/reverse clutch or band.
First gear is the forward clutch and the low/reverse band or clutch - this holds the ring gear stationary and drives the sun gear, I think.
The low/reverse band or clutch is the one engaged last, so that it gets all the slip going into either reverse or forward range. The others are used less often, so get less wear. Usually the low/reverse clutch or band is heavier or has more frictions plates to make up the difference, but they still wear more.
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!