There's some good information, including the ONLY correct fluid to use in this transmission, on the club website at http://www.imperialclub.com/Yr/1990/Repair/a604.htmCall me nuts, I just purchased a 93 Imperial and I've got a few questions about the transmission. For the most part it shifts and drives great.There is a hard shift between gears mostly when cold and a slight vibration when I come off the highway and I'm stopped.I'm going to have the transmission serviced and I was wondering if there is anything other than a flush and fill with a filter change that can be done that could correct this. What would be considered a 'tune up' and do you think that might correct the vibration.