Have to slam tailgate

[catch2otwo]

Ive been digging through old threads regarding tailgate alignment issues. Alot of these threads deal with aftermarket tailgates. Not sure if mine is aftermarket or not.

When I close it, I have to slam it in order for it to latch. If I gently close it, the tailgate will pretty much get hung up well before the latch even comes close to closing. The two locating tabs hit the bed and interfere so much that unless you slam it you will not be able to close it.

In order to open, I have to really yank on it to open it. Where do I start with adjusting? I haven't put a square on the floor to see if the bedsides are falling in or not.