No third gear or doesnt want to shift to it.

I got a C4 transmission form a wrecker and he assured me it was in good shape. I installed a B&M shift kit following the instructions to a T. Fluid level is good. Bands are adjusted.

Reverse works good. I can put it in drive and it will shift 1st to second with a bit of hesitation but when I get upto speed it it seems to shift into third and then it just revs like it is in neutral. If I stomp on it harder and get the revs up though, it starts to pull but man it does rev really high.

Couple questions

I keep reading about a vacuum line going to the transmission. I cant find a spot for one on mine. Is it only AOD's that have them?

Is it maybe the modulator that came with the shift kit thats giving me problems or maybe needs adjustment?

Or is it maybe a good idea to pull the valve body and check for problems there?

Maybe the tranny was bad lol.

Any help and advice would be great

Thanks

The C4 modulator needs to be connected to manifold vacuum. If it's not, or the modulator is not working right, you'll have trouble with 3rd or it won't get there at all. An AOD uses a TV cable and no vacuum modulator - different animal all together.

The modulator has a recessed vacuum connection on the very back of it. It is easy to miss if you are unfamiliar with them. Connect it to the manifold vacuum with a (1/4" or 3/16") metal line. a short piece of rubber hose at each end of the metal line is used to make the connections. If you try to use a rubber hose it will colapse under the vacuum and you will have problems. The vacuum hose is necessary to normal shifting. You should also make sure your kick down is adjusted to allow .060" between the adjuster screw and the kick-down lever at wide open throttle with the kick-down linkage fully depressed.
Make sure the bands are properly adjusted and oil levels are at the correct level and with the correct fluid. (type "F" or Mercon V)