Therein lies one of the big problems in changing engines, future titling issues. I think it's also the main reason the states went away from using the engine number. Every state has a process for resolving the issue. If you have a vehicle where the engine number was used but you don't have that engine any longer you'll need to contact your state licensing authority (where you get your tag/title transfered) to find out what their process is.

Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.