They don't hand out the location of the confidential VIN stamped on the frame to just anyone. Normally, only people cleared for access to the NATB data base can get that information, and it's a closely held group. When I was still a cop, I used a friend of mine who was an Indiana State Police auto theft detective on cases where we needed to check for the confidential VIN, and even though we were buds he had to come out and do the search and check himself, no "look here on the frame". Plus, it's not always the entire VIN, sometimes it's a partial number that you need the NATB to decode (sorry, National Automobile Theft Bureau).
My suggestion is that you contact your state police, I'm 99.9% sure they'll have Auto Theft detectives in various areas of Michigan. The downside is, if the thing is stolen (or partially stolen anyway, the 1500 VIN is obviously clean) they'll probably take the truck. In similar cases I've seen people get them back after dealing with the actual owner or insurance company, but it's a crap shoot.
As old as the truck is, it's probably an innocent cab swap.... The 4.7 dumped, they had a rotted out 2500 with good running gear, so they put good cab and bed on good frame. The unknown is Colorado, for a couple of reasons. First, if you get a trooper doing your numbers check who knows something about vehicles, he's gonna notice that it's not a 1500. If he happens to be a Ram aficionado, he'll know a Hemisphere didn't come in a 2002 anything. He could snatch your truck for further investigation, and who knows where that goes.
Second is emissions. Do you know the emissions rules for where you plan to move in Colorado? I know some areas require emissions inspections, others don't. If you're in an area that does, there's different emissions rules for half tons and 3/4 tons....3/4 might even be exempt. But since you're titled as a 1500, if you have to test, you'll have to pass the tailpipe test for a 4.7 with a Hemi. Plus, if the emissions guy knows anything, he'll know that engine does not match the truck and no sticker for you.
You've got a lot to think about....