Where are you seeing this notation? When you sign in to your account, is it on that first page underneath your existing II account number?
On that page are you also seeing your new II account number?

Sorry for all the questions, Steve, but I'm trying to compare what you're seeing with the way my II account looks. On my first page after sign-in, both account numbers (the old/individual and new/corporate) are listed with a "Select" button for each. Under the old account number there's a similar notation to what you're seeing - "PRE MVCI CLUB DESTINATION MEMBERS ORLANDO,FL,USA" - but it doesn't include anything about a specific Unit. Under my new account number there is this notation - "MARRIOTT VACATION CLUB DESTINATIONS." If you're not seeing anything related to a new account number, then perhaps you're right and that odd Unit reference is a placeholder.
(One other place to check for the new II account number is in your my-vacationclub.com account. Sign in, click on "Manage My Account" then "My Profile." Scroll down through the Account Details - in our info Don is listed first with one MVC number and our new II account number, then I'm listed second with another MVC number and our original II account number.)