From what I was told by a salesman at the dealership... That couldn't be done because of the difference in the regular bed and the RAM box bed of the body or something like that (its been awhile since what I was told so I could be mistaken). The salesman could also be wrong to.
I was hoping to do the same thing awhile back when I was told no.
I had even found a RAM box bed in great shape and my color on eBay for under $1000 shipped. The RAM box is the one option I wanted and wasn't able to get.