I had the truck out the day before, everything was ok. I let it set overnight and now it wont shift up or down in drive like it is stuck in third gear. You can shift into reverse gear, one or two and also pull it out of drive into second and it will down shift to second. The fluid level is good, changed at 52k the truck has 62k on it now. Any help would be appreciated!

 

look at the linkage that sits and top of the transmission where the lever for your colunm shift is. its a steel rod but its a cable driven, could have broke or fell off.it comes off the throttle cable.i know im not eplaining it well, my mind is not working right not enough coffeeLOL

 

check all the wires going into the tranny, might of fell off or get knocked off somehow

 

Governor Pressure Solenoid and sensor - common problem on these trucks. Check JRV's posts he's in a few threads that explain it, and one even has a picture of it in the valve body. Not a a hard fix, few hundred for parts.