Howdy guys..I should first mention that I am not interested in buying a 400!!! Ha... My 89 has actually been a great tranny for a mostly road tripping & light wheeling guy like me. A couple of months ago my TC wasn't locking in overdrive. I got a some good tips from you guys and things somehow solved themselves for a while. Now the problem is back and again the TC won't always lock up in OD. Sometimes it will engage once my tranny temp gauge hits about 150. Ive checked the wires and they seem to be tightly connected and also done the brake test on the highway. When it is working and I hit the brake it unlocks immediately and the rpms go up. So now Im thinking it is time to get into the pan. From what Ive read the solenoid could be tired or possibly the pressure switch. Im thinking the pressure switch might be a bit off. When Im real light on the throttle (on the highway)in OD and I approach a slight grade sometimes it will decide to lock up?? Seems like an unlikely time for it to lock up???