I have a 1998 oldsmobile bravada awd. It has the 4.3 paired with a 4l60e transmission. Never once have I noticed any transmission problems. I took it through some deep mud earlier this week. Had to be pulled out. 4 days later it went from driving fine went to turn in by my work and it shook violently then stopped. Tried to put it in parked and back into gear and it didn't go anywhere. Got it pulled to work and now it is sitting in the parking lot. It was low on fluid so I pull in 2 gallons of dextron fluid which it drained all on the ground. What could be wrong with it.