I was chasing horses back into the pasture at our place and i hit a rut in our road at 20MPH. then a small mole hill. my truck pops into neutral gear EVERY time. i looked under the truck and i seem to have a small leak at the shifter input to the tranny..

truck shifts good and strong. no slack in the cable either..

im tempted to throw in my replacement tranny from my parts truck.. can i easily solve this issue with grommets or an adjustment? could bad motor mounts do this?

 

Check the shifter linkage closely. Most likely a missing or worn bushing in the shift linkage.

 

Check the motor mounts, rear trans mount, shift linkage, and, scarily enough.... body mounts. If the cab can bounce around on the frame, it can pull the trans out of gear.