for a little while my truck would sound like it was spinning or grinding gears when in reverse and not it will not back up at all, it will go into drive and everything but not reverse,

it sounds l like you need tranny work done you might have stripped your reverse gear

have you tried shifting it haha jk you probably need a new tranie

Engine, trani, year?

You need to have your trans rebuilt or replaced. It is starting to come apart internally.

need a new transmission