What is this plastic part?

Any idea what this part is / where it goes? After I got my truck back from a detail and some body and paint work, this was laying in the bed. I thought it was a bumper of some sort, but it’s hard plastic.

 

Found a photo, maybe a bed support or alignment plug, but it’s hard plastic and doesn’t look like it’s ever had weight or wear on it. I wonder how critical it is…

 

It's for bed alignment. There's 2 of them on the left side frame. One front and one in the back. They line up with holes in the bed cross members.

 

So not a critical part I’m assuming, meaning the bed doesn’t need to be removed to reinstall it?

 

It's not a critical part. You would have to unbolt and lift the bed to put it back. If your bed is all lined up with the cab I wouldn't worry about it.