MLDGS – LUGG RACK – DECORE GP – TAILGATE

The 4th box from the right on the second line indicates the Mouldings - Luggage Rack - Decor Group and Tailgate codes. In the build sheets I've reviewed so far, a code for the deluxe interior in the Warranty Plant Code (signified by a "B", see Warranty Plant Code entry below) usually triggers a 5 code in this box.
The Interior Decor Group option was comprised of:
Special interior trim consisting of Pony upholstery and wood-grain dash appointments
Deluxe wood-grain steering wheel
Red & white door courtesy lights
Pistol grip door handles

Rocker Panel Mouldings were not coded for Mustangs. They were either standard equipment, or deleted in favor of the GT option.

MLDGS – LUGG RACK – DECORE GP – TAILGATE

2	Rocker Panel Mouldings	G	Luggage Rack
3	Bright Metal Mouldings	L	Deluxe Rack & Bright Metal Mouldings
5	Décor Group	P	Deluxe Luggage Rack
6	Rocker & Décor