I have a 69 f250 with a c4 that may be a bit later than 69. Recently it started having problems engaging in drive after sitting for a hour or so. Reverse is fine. I find reving the engine a while in 1st will finally get the tranny to grab / engage after slipping a bit. Once the it engages in 1st I drive, shift to 2nd then to drive. After that it seems to act normal and shift fine through the gears, even from a dead stop in drive. I've drained the pan 3 times in hopes of flushing it out. Each time making sure to drive it for a bit before topping it Off to correct level, running and in park. What could this be?

 

I'm not an auto tranny guy, but sounds like it should be checked by someone competent. Around here, W. Texas, we can get a bench rebuild for about $400 if we drop and haul the tranny to the shop...they get about $800 if you just drive it in and leave it, and they pull/rebuild/reinstall.

 

UPDATE:
Tranny has now quit engaging in any forward gears, reverse is still good. If it is put in 1st and given a few seconds you'll here is finally drop in (engine sounds like load has been placed on it) but there is no movement under acceleration. There will be a slight pull under high revs but mostly slipping.

 

UPDATE:
Tranny has now quit engaging in any forward gears, reverse is still good. If it is put in 1st and given a few seconds you'll here is finally drop in (engine sounds like load has been placed on it) but there is no movement under acceleration. There will be a slight pull under high revs but mostly slipping.

 

You have the classic symptoms of worn seals causing low fluid pressure which is causing your problems. Typically after the fluid warms up the seals it will engage until the leaks get worse. There are some other possible causes, but in any case you are in for a rebuild.