Just bought a 2002 Dodge ram 1500 with 8 lug wheels

[18CrewDually]

Bring it to a local shop and ask them to plug in with a scanner to read the VIN.

It is definitely a body swapped cab on a 2500 chassis.

My state goes by the VIN behind the windshield. A second VIN verification is the door sticker. If not available, a third verification is the build tag behind the passenger side headlight. The codes can be looked up and will tell you the entire build of the truck (CAB).
When it comes to buying chassis/running gear parts none of that VIN matters. The VIN will only be for registration purposes.
Also on the driver side frame rail should have the VIN of the chassis donor truck unless they flap wheeled it off or filled it with weld and then smoothed it out making it undetectable.
Register it as a 1500 and play dumb.
Sounds like you have 2 bastardized trucks.

 

[Hootbro]

What a mess. The only way I can see it getting sorted especially if moving to a emissions testing area/state, is to get the vehicle deemed and titled as what the frame and powertrain is.

 

[Marshall]

Insurance on this could be a problem as well, But I know nothing about auto insurance in the US.

 

[aszumilo]

One problem I see with the smog check. Here in Nevada, the smog machines plug into the OBD port and transmit the results to DMV. If the VIN, in the PCM, does not match the VIN on the Cab/title/Registration, DMV will not receive the proper results and may show the truck as not having the smog check done. Other states may be different.

 

[GTyankee]

20 year old truck would very seldom have the original engine

If the VIN & other Identification numbers are not reported stolen, who cares

Someone mentioned either VIN or partial Vin on passenger side Radiator Shroud, that would be looking at the numbers from inside of the engine compartment

Another spot would be on the frame, pretty tight against the cab, under the driver's seat.
I have done a few body off frame, rubber mount replacements on 1950s - 1970s vehicles

 

[Andrei20]

I'd be actually happy if that happened to me, to buy a 2500/3500 chassis with a 1500 badge on the door at the price of a half ton. I'd be looking for a 5.9 Cummins to swap into it.

 

[czervika]

Folks, if I was going to stay in MI I think I would be all set. But I am moving to CO in a few months. I think they want to do a VIN inspection before they will register any out of state vehicles for the first time. Does anyone know whether the troopers in CO are looking for matching engine / Frame information ? Its a 22 YO truck, unfortunately I had no idea I was buying a bastardized truck cobbled together from different parts..... The engine model / size is not going to match what is linked to the VIN data.

Lived there for 30+ years. All they do is match your title to the VIN on the windshield and door. They usually do t go looking at the "hidden" VINs on frame and body.

Edit, I should add I rebuilt a few vehicles there and had to go through the inspection process several times for that and purchases from out of state.