My truck will act like it’s in drive no matter what gear I put it in it’s like it starts slipping when put in park or reverse but drives and shifts in neutral drive 1 or 2 when you turn it off it will go into park reverse and neutral but only when you turn it off

 

Check the shifter linkage or possible damaged rooster comb.

 

Check the shifter as Moparite had said. If the shifter is okay. Then the problem is with is inside the transmission. The front and back drums have welded themselves together. I have seen the happen before.

 

same thing happened on my old ranger. I forgot exactly what parts in the transmission welded together like master tech said. I recommend checking the shifter and if that doesn't work take it to a trans shop.