I had known my truck had been a little "off" for a while after I got it home, but it took me about 20,000mi to measure it and do something about it. It was actually skewed and off center. I crawled under the truck and took the following quick measurements from the outside of the frame to the return flange under the rockers where the two metals meet.
Front where the door meets the fender:
LF - 12 & 7/8"
RF - 12 1/2"
Rear of the cab:
LR - 12"
RR - 12 3/4"
Thanks to some forum research I did, I decided to move this over myself, and I made a video after the fact showing what to look for, and how I fixed it. Sorry for the wind noise - I didn't have time to drive to the shop to make the video, but figured this would do. The video shows what to look for to determine if your truck is out of alignment, and I also go through the motions of what I had to do to fix it.
Again... this is something that would be easy to do with the proper tools. It's not for everyone, so be sure to make a good judgement call if you can do this yourself, and if you've got the proper tools to do it. Like I mentioned in the video, I don't think the cab could be moved over without some form of jack or hydrolic force just due to the weight of the cab, but if you've got room to make a board lever, or a small bottle jack will do the job no problem. I prefered the bottle jack, as I could watch my measurement as I jacked the cab over to assure I didn't go to far.
As always, you're responsible for knowing your limits, and responsible for anything that happens should you choose to do this yourself. Consult a mechanic before attempting any repairs. Proceed at your own risk.