it won't enguage in any gear or wont shift from first?
did it just happen with no warning?
first i would check your linkage on the side of the tranny, then id pull the pan and make sure the linkage is good inside the tranny. if those aren't it, it may be a pump problem.
i had one do almost, if not the same thing. i was moving sand around with my plow and shifted into reverse and nothing, drive nothing, we checked everything, all was good, nice red color in the fluid. i got pissed (the polls were on either side of my door so i couldn't get out) and put it in reverse and it enguaged and went, i was stupid to stop and then it didn't work again, again i punched it and it took off, i backed it out of the way. the funny thing is this was 3 weeks after i bought the truck and the PO said that his buddy rebuild the trans and said its unbreakable, i guess im hard on stuff /forums/images/graemlins/whistling.gif /forums/images/graemlins/whistling.gif
ive been too lazy to tear it apart to find what it was but my best guess is the pump and im betting you have the same problem.
there was no noises or anything.