To flush or not to flush...That is the question; Automatic transmissions that is. I have a 1991.5 dodge d350 that I'm going through to get ready for dd duty. I believe it has the a518 automatic with overdrive. I am resealing a few systems and changing fluids and intend to drop the pan of the transmission and change the filter/fluid. I have a friend with a transmission flushing machine. He runs a lube spot. I asked him about flushing the trans, and he said unless it's slipping or shifting hard, don't bother. I would risk dislodging gunk that's found a happy place and gaining trans issues. I'm already set on changing the trans fluid for peace of mind, as well as knowing a. What fluid is in there and b. That my filter and levels are correct. Opinions on these sort of trans flushes? Worth the risk? First hand experience of everything going to hell in a handbasket following any trans flush? Currently my trans shifts as it should and that allows me to sleep at night. I have flushed fluids before in my 7.3 with the e4od, but that was into a bucket under the power of the transmissions pump itself.