84 300SD. Tranny looks like a recent rebuild, ink stamped part numbers clearly readable on friction discs and bands. The B3 friction disc closest to the 1st outer plate, the thick one with 1 concave side, broke into 3 pieces and the friction material is almost completly worn off and the inner teeth are all chewed up. The other 3 disks in the pack don't look bad at all.

1. What happened first? The disk breaking or the material wearing off?

2. Is this a symptom of something done wrong during the rebuild, or do these discs just fail sometimes?

Thanks in advance.