ALehman,
Depending what you are doing withyour truck (pulling heavy trailers ,sled pulling, mud racing ... ) what mods you will need.
ATS, DTT and the other after market transmission part suppliers will help with you with your decision (I like to beef up a little more than I need to).
Vavle body basically changes gears for you. Fluid pressure (or lack of) changes gears. Vacuum from the engine used be determing factor but now electronics determine when shifts are to be made. ( Of course the governor and the tc play apart in changing gears. )
I believe your 94 is electronic controlled but it mite be vacuum.