I just had my E40D rebuilt because it started whining and wouldn't go forward or reverse. The rebuilder that did the tranny has 21 years experience. He said what happened was a large (6"-8"diameter) snap ring let loose which allowed a large cluster of hard parts to start to move back and forth. This cluster put pressure up against the torque converter causing my temp to rise to 220 plus. Something called a sprag let go and everything then went real bad. Total cost for the removal, rebuild with all updates including a redesigned snap ring that can't come out and all new solenoids, install with Amsoil was $1,905.00. It shifts great. No more searching for a gear. It kicks down now quicker whereas before sometimes I couldn't get it to downshift to pass on freeway. No whishy-whashy shifts but not harsh either. He said the snap ring issue is a common problem that he sees.