Yes i have a C6 transmission out of a 1986 Econoline. I got the 351HO and the tranny and put them straight into my 1979 F100. I had done some minor bolt on to the motor and put a B&M Shift kit in the tranny. Well when i started driving it, it would shift too soon out of first and seemed like it would just go to third too fast and wouldn't shift right. The modulator valve had no effect. And it had plenty of fluid. Well i would put it in second to take off then shift into third when i got up to speed. A couple of days ago i noticed that when i barly gave any gas while in second it would jam down into first. It would be in second while decceleration and while the motor wasn't reving. I don't have a kickdown rod. Well today i came home from school and i may have spun a tire a little bit. but not anymore than usual and i didn't over rev or anything. Well i got it home and it set for about a hour. Then i got it in to go to work and fired it up and heard a whining noise. I couldn't quite hear where it was coming from. Then i put it in drive and it just started whining louder. when you give it alot of gas it would move but barly. Second and First was the same way. Now when i put it in reverse it goes just fine. SO reverse works but none of the forward gears. I put some more fluid in it to be sure it had enough and still no difference. I am pretty sure the shift kit was installed properly. Can anyone tell me the problem or any help. any would be great. Thank You

 

No forward gears, sounds like forward clutch problems. I believe an overhaul is in your future. If the tranny was shifting early after installing the shift-kit and not before, there may be a problem with the install causing low pressure upshifts (damaging the forward clutch). Are you sure the pin is behind the modulator valve? I'm afraid it's to late for any external fixes, it's all an inside job now.

 

true true true...check modulator first. if not rebuild...if you trash it i need parts LOL!