You do need a physical VIN check.
It was a pain for my sister in town, but it is a breeze here in Clear Creek. The sheriff's office is in the same building, so very easy. In fact, so easy that my sister just drove her vehicle up the hill just to get the VIN check.
Swapping the rear end (whether full axle or just the third member) is a one day job, can be done in a driveway with some jackstands. I'm SURE that you can do better than taking it "to a shop" to get it done. x2 on checking Robbie's availability first.
That is a very nice looking 40!