When my truck is in neutral i can push it forward but when i try to push it in reverse it locks up still in neutral what could it be need help

 

Locked Front Hubs?

 

Rear brake problem? Shoes grabbing due to self adjust mechanism jacked up? Or e-brake causing probs?

You're sure it's trans?

 

Not sure what it is it seem like a rearend problem not trans

 

I would inspect the rear brakes. Pull the drums off and inspect brake mechanicals. If that visibly appears ok, then, while in neutral and drums still off, turn the driveshaft in both directions to see if your problem is actually in the 3rd member(gears).