Stolen vehicles are often branded if recovery happens after the initial claim is closed and settled. Besides the insurance company not wanting to spend time doing a missing parts analysis, or try to guess how hard it was rode, it provides a was to make a vehicle go un-missing in DMV databases etc. And probably helps reduce fraud, otherwise it would be too easy to stash your rig a while...
https://www.edmunds.com/car-buying/w...e-vehicle.html
So, this is probably legit but I'd certainly give it a VERY thorough inspection including mileage readings off the PCM (and make sure there's no VIN-discrepancy code stored in the memory.... clusters are easy to swap the the PCM knows).