Ford used different part numbers to represent different stages of that parts process, in this case a fiberglass forming number and a finished item number. The C7ZB-6331486-BW (and 487-BW) are the finished item numbers, which are called out on the assembly drawings (with an appropriate painted finish designation). The C7AB-6331070-BW may be the "as formed", "pre-holes drilled" version. Instead of a paper tag to identify each, both numbers were embossed into the part.
Note: For 67 service, the MPC calls out a C7ZZ- and a C8ZZ- part number for RH/LH panels. For 68 service, both sides are C8ZZ-.
Jim