It depends on where you are with the way a registration works,over here the registration is tied to the chassis,so if you've a rusty 1991 defender,and put a new chassis under all the original bodywork and running gear you technically have a 2015 defender,in the UK I think it is different. I think the main issue isn't actually in the states,but the original countries that the defender came from,it could be a stolen defender in the country of origin,with the VIN scraped off and replaced with one of a car they have the registration for,which could have been exported to africa,which is why it is important for the numbers to match up when they are arriving in the states.
I think that law is there for your benefit,fixing defenders is an unending task,which will probably cost you your marriage and your job :sombrero: