I have a 1963 Riviera with a numbers matching engine but I am trying to determine if it is a 401 (Wildcat 445) or a 425 (Wildcat 465). The air cleaner looks original says wildcat 465 so it makes me think it is a 425 but I just want to make sure some previous owner did not just swap the air cleaner with a true 425. The engine id is JT538. Any help would be appreciated.
Just a shot in the dark, but according to http://www.buicks.net/shop/reference/engine_ident_63_75.html the JT is a 1963 401. Devon
