Transmission stuck in low. Need help ASAP!

I just got my 15 speed in and it is stuck in either low or deep reduction, not sure as the deep reduction splitter does not seem to make a difference. Either way it will not split to the high side. When I flip the splitter I hear the clunk but it is still in low. I can even stop and put it into 6th, but then when I let the clutch out it is obviously in 1st. Any ideas? I double checked all my air lines and they are hooked up correct. There was some corrosion inside the air filter/regulator so I changed that before I installed it. Could a valve be stuck somewhere? I checked my air diagrams and in hi, low, and deep reduction all the correct lines at the valve selector where charged. I don't know what to do here. I need this truck in a few days and I can't put my old tranny back in cause I already cut my driveshaft.

 

It was not rebuilt, just a used one. I have double checked my lines several times and they are right acccording to all my shcematics.

 

Is a 1/4" supply line enough to the transmission?

 

Just digging through diagrams now. Going to double check all air lines again tomarrow for proper connections and to make sure proper lines are charged when in hi, lo, ect. At this point i'm thinking, stuck valve, incorrect air line, or not proper flow from tank. Though i'm sure I read somewhere that 1/4" was enough.

 

Never pulled them apart before. Is it just a valve in there or do I need to watch out when I take the cover off or I will have a hundred little things falling out?