First Line
10D - Build Date. First 2 digits (always numbers) represent the month of manufacture, the last digit (always a letter) represents the week in that month, therefore 10D is the 4th week of October.
047 - Plant use code
509 - Plant use code
Second Line
4 - GM line (1 - Chevrolet, 2 - Pontiac, 3 - Oldsmobile, 4 - Buick)
H - H-Body (found on all Trim Tags)
S07 - Car Model (see VIN # Decoder)
138415 - Sequential Serial Number (same as last 6 digits of the VIN#)
Third Line
69L - Exterior paint colour (see RPO Code list)
69U - Exterior paint colour OR vinyl roof colour (See RPO Code list)
11A - Stripe code BUT could also be a vinyl roof colour code (See RPO Code list)
64N - Interior trim colour and type (See RPO Code list)
1977 saw all 2nd Gen. GM H-Body production shift to Ste. Therese, Quebec. All '77 models had the same style trim tags that the Ste. Therese plant introduced the previous year.
Build Date >>>>>>>>>>>>>>> <<<<<<<<<<<<< Plant use
Body Style >>>>>>>>>>>>>> <<<<<<<<<<<< Serial #
Paint Codes >>>>>>>>>>>>> <<<<<<<<<<<< Trim Code