We have used Aerostars in our company for 20 years. All 4WD. We must like them.. And we do allot of logging roads with them. Our first 96 and last van we purchased was acquired two years ago with just 60k miles on it. Ive been bouncing around the idea of changing out the transmission with a 97 5r55E model and suddenly due to a torque converter failure went full bore with it. So to help with others that may want to consider this.. The 4r55e (96) and the 5r55e (97) are almost physically the same and will bolt right up. Difference is the starter changed in 97 so you will need to replace your 96 model starter with a 97 unit. The 5r55e has an OSS (output shaft sensor) that the 4r55e does not have. Using the 96 harness and computer will shift the new trans just like the old one. I.E. only 4 forward gears. You need the OSS sensor wiring run to the PCM, and a 97 PCM to make the thing use all 5 gears. Im actually considering an aftermarket controller. We have a 97 with a ton of miles on it that is going away soon and am going to take my harness and PCM from it. I have used the 97 PCM in this van to try and get 5 gears in the past with some success.. But without the sensor it winds out before shifting to 2nd. Im still looking for a harness diagram for a 97 Aerostar to document this better and will post it here when I do. Meanwhile.. any suggestions for headers that will fairly easily adapt to these vans?