More stuff here on max ujoint angles vs shaft speed:
SHAFT RPM OPERATING ANGLE
5000 3.25?
4500 3.67?
4000 4.25?
3500 5.00?
3000 5.83?
2500 7.00?
2000 8.67?
1500 11.5?

Now consider that with our a/t's, the dshaft is rotating FASTER than the engine. for example, with a .70 od ratio, at 2800rpms, the shaft is doing 4000rpms, so the angle limit is 4.25* I think ours exceeds that. The result is shortened ujoint life. Average life is 3000hrs. Doubling the angle halves the life, and differences in angle also shorten the life, but I haven't found a factor for that yet.