been driving my truck for a few months now in drive cause overdrive wouldn't engage when i got it.3 or 4 weeks ago i put some seafoam in it just for ****zngigglez. no change.

on my way home today i was playing with it and got it to shift into overdrive by reving it up to about 3 grand and letting off. when i took off from the next stop light it shifted when i let off the gas when i felt it slip.next stop light it shifted on its own.


so in short WOOHOO

 

I have heard that non computer controlled transmissions won't engauge until higher RPMs. So if you have higher gears that could be the culprit. I know that is true for the GM 700R4, because that is a popular swap into full size Jeeps, and many of them came with 2.73 gears, and the 700R4 won't go into OD until like 80 MPH with those kind of gears.