i just got my truck going here and i got no 4th gear. everything else is workin good shifts nice and firm. ill be running down the hwy in 3rd shift to overdrive and nothing if i let off the rpm goes down to where i think it should be in 4th but it won't hold it. its out of a 89. ive had the pan off and everything there is good the oils not burnt up or anything not sure what else it could be.

 

Valves sticking in the valve body? Are your servos on the side moving...can you push them in?

 

Did you check the 4 pin plug on the side of the transmission? It locks/unlocks the converter and allows it to shift into 4th.
Some people that do a lot of aftermarket work or projects just run a switch to that plug and flick it on in the cab so it'll shift into 4th. I don't like that myself but Check your plug and make sure its not burned or anything.

If not then as yenko said, i'd check the valve body.

 

I Re read your post. If it acts like it shifted into 4th but nothings there it needs new clutches. If it Stays in 3rd and doesn't attempt to shift try the above.

 

no valves sticking, servos good that was all checked i do believe

 

i got nothing goin on with that plug. i was told it was only for locking up the converter and doesn't have much to do with getting 4th.

 

You still haven't said if the transmission acts like it's shifting but slips or if it doesn't try to shift into 4th at all.
If it sits there and just slips like it's probably burned up.
If the governor on the side of the transmission is good, make sure your tv cable is adjusted right. Also check the shifter linkage to make sure it's going all the way to 4th.
A guy on streetrodding.com had a similar problem where It wouldn't shift into 4th when the 4pin plug was plugged in. When unplugged he would get 4th but the converter wouldn't lock and when plugged in 4th was gone all together. You could do a test on that.
If you still don't have 4th i'd guess the clutches are gone.

Just some guesses I figure you could try. Can't hurt any.

 

thanks but i finally just took it to a shop to get pulled

check her out http://www.youtube.com/watch?v=CDHqFufRy6A

 

What happened? I was wondering I am have a simliar problem. Mine will shift in to 4th but lock up will not happen. I just ordered the b&m lock up kit for truck that did not come with a 700R4 tranny. It should be here sometime tomorrow.