The paint codes on the SPID label in the trunk will be the numbers ending with the letters:
U-Upper
L-Lower
M-Middle
These are refered to as the short numbers. Single color cars will only have a number ending with the letter U. I.e. a GN will have the paint code 19U and a WH1 designer car will have the codes 19U,19L and 15M.
Only the WH1 and the 1987 Regals have the long paint codes on the label. They are usually found after the list of codes and usually have the letters WA starting at the beginning of the row. I.e on an 87 GN you would typically see WA 0848( or just 848) and maybe the words DIS LAC. A WH1 car would have WA 0848 0848 8573.
The short numbers can also be found on the cowl tag.
The other codes are the colors and material type of trim such as vinyl tops,seats and body side moldings.
A-Accent. Stripe or decal color
T-Trim. Vinyl top & body side molding color
I-Interior basic color
All other letter suffixes denote interior color and fabric type.
I.e. a 85-87 GN will have the 2 interior codes 82I and 82C.