We commonly referred to the myriad of identification procedures as "creative part number engineering". Ford engineering departments had a lot of leeway in assigning part numbers, and they took full advantage of that. They were under corporate pressure to produce a product - a car. That's why the RH lamp is D0ZB-13707-C, the LH is D0ZB-13K705-C and the service stock number is C9ZZ-13763-A for both, or is it. It was in the service department phase that a lot (it is two words) of the numbering problems came to light and were straightened out. A Ford "replacement" part had to work, not be Concourse correct.
In some situations, the housing, the lens, the bulb and the bracket were serviced (and sold) separately. In others, one number contained all those items. Consider it a (frustrating) treasure hunt.
Jim