its going to be a cluster ****
as mentioned the frame will be more narrow so new holes there no big deal
biggest problem you will have is the gap between the bed and cab because the axle sits a few inches back
also the bed lines will not match cab line
the end of the bed will be sitting up unless you notch it because the frame is going to be longer then the bed itself
making a rear bumper work will be a pita because of the dimension differences
hardest part is getting fuel to flow correctly because you basically have to have 2 45* or 2 90*elbows on it to get the fuel to flow from your fuel door to your rear mounted fuel tank , unless you do a fuel door hole in the rear of bed