General Cutlass SX455 Q&A

Greg & Alan - super helpful, thank you. I have a 71 SX convertible that I have owned for 16 years +/- and while everything checks out in the "spotter tips" I've always had that doubt in the back of my mind. This is the best explanation I have seen so far about the 71.

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That is correct, the 1971's only are rather simple to verify. The 1970 on the other hand, is a whole different animal.

Thanks, so documentation is not needed to 100% verify a factory 1971 SX provided (1) the first 4 digits of the car VIN start with 3425 (coupe) or 3426 (convertible), (2) the engine is a 455 and (3) the engine # matches the car VIN ... correct?

This should make the search for a real 1971 SX convertible easier.

The short answer to your question is yes, yes, yes and no. In 1971 the 455 engine was not available in any Cutlass model other than the Supreme hardtop and convertible under the option Y79 (SX). Any 1971 Supreme either coupe or convertible, with a matching number 455 engine or a matching number T-400 trans, would be an original SX. There was no other way to get either item without being an SX.

The attached document includes the following statement when referencing the 1971 455 engine - "This engine was only available in the SX and the Vista-Cruiser wagon, and was also the only way to get a 455 in a Cutlass Supreme Coupe in 1971." Is this statement correct? If yes, can the statement be extended to the Cutlass Supreme Convertible? If yes, wouldn't this mean any 1971 Cutlass Supreme Coupe and/or Convertible with a 455 matching numbers engine was an original factory SX? Were there any 1971 Cutlass Supreme's with a 455 engine that were not an SX?