The 604 is a great tranny that powered many minivans and cars, but they got a bad Rep because people were using the wrong fluid. If you dump Dextron in one it will ruin it. Gotta use ATF+4. I believe it was the first computer controlled 4 speed tranny(?) The solenoid pak makes a marvelous sounding noise whenever you stop (If you like such noises) Kinda like that after-run sound like when you turn a car on with cheap gas that keeps running for a few seconds, but you can barely hear it.