From Sloan: there were 3,627 LeSabre convertibles produced in 1974 model year. 1,613 had a 455 V8. Here are the versions of the 1,613 engines: L72 (455, 2 bbl): Flint: 0 Wilmington: 124 Fairfax: 106 L74 (455 4 bbl): Flint: 0 Wilmington: 454 Fairfax: 732 L76 (455 Hi Performance): Flint: 1 Wilmington: 77 Fairfax: 119 Total: 197 A page I have from the 1974 Buick Service Manual (page OA-6) does call the W code engine a 455 4bbl "E" Stage 1 with dual exhaust. The 7th digit in the VIN (before the sequence) is the plant: H = Flint, X = Fairfax, Y = Wilmington. If you want to contact Sloan Museum, the number I had (2 years ago) was 810-237-3450, you would be looking for what they call the "micro-fiche" info that shows all the options on the car, if you provide them the VIN. They have '72 - '80 model years covered. This is a good way to be double-sure it is Stage 1. It cost $25 and they mail you the information in about a week. Email is sloan@sloanlongway.org. The guy who helped me and gave me the engine info was the curatorial assistant (Andy).