I solved my over drive problem this weekend. I tried every fix except for replacing the automatic solenoid. My truck is a 1988 SWB with a automatic.I was at a local pic-u-park a couple of months ago and found a 1989 v6 in the yard and pulled the solenoid from the truck for $15. The connectors on the 89 are different then the 88. I switched out the connectors on the 89 with the 88 connectors and installed the solenoid loop and my truck trans works perfect. FYI if your over drive doesn't work and the problem is the OD solo you can pull it from a 89 v6 if you change out the connection points with the 87 or 88 harness.