These interior trim codes for 1955-57 Chevrolet passenger car models decode the “TRIM” line on the cowl tag. This chart is used in conjunction with the Cowl Tag Identification Guide to decode color, style and material of the interior upholstery on all 1955, 1956 and 1957 passenger car models.

Information courtesy of Classic Industries.

https://paddockparts.com/wp-content/uploads/2012/03/1957_Chevy_InteriorTrimCodes.pdf