"SOCOM" is actually the acronym for "Special Operations Command" which is The U.S. Joint and Combined Service headquarters based in Florida-- what's known as a "Unified Command". As such, they have specific units assigned from the Army, Navy, Marines and Air Force depending on the mission at hand. So the short answer to your question is the vehicle codes and bumper numbers for "SOCOM" are only those vehicles assigned directly to the headquarters unit. Operational units assigned to SOCOM for missions would have thier own bumper numbers, for example, Ranger Regiment, Navy Seals, 160th SOAR, etc., would have thier own vehicle ID system, if any. My experience with these units is they don't mark vehicles during operations, but they might while in garrison. Supporting and attached logistical forces may also mark thier vehicles with specific IDs, it just depends on what unit within SOCOM you are talking about, and the specific circumstances. Hope that helps.
VR, Russ