MIL ACFT IS INFORMED 30 MINS AFTER IT HAPPENED THAT THEY WERE INVOLVED IN AN NMAC WITH A GA ACFT NEAR SDM ARPT; CA.

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WE WERE CLBING THROUGH APPROX 2700 FT MSL; IN A R TURN TO DOWNWIND. WE WERE OPERATING VFR; MAINTAINING CLR OF THE SAN CLASS B AIRSPACE TO THE N AND THE MEXICO BORDER TO THE S. BROWN TWR HANDED US OFF TO SOCAL APCH; AND WHEN THE COPLT CHKED IN; THEY CALLED KING AIR TFC. I DO NOT REMEMBER WHERE THE TFC WAS CALLED; BUT I REMEMBER THE COPLT RESPOND THAT WE WERE 'SEARCHING FOR TFC.' WE NEVER DID SEE THE TFC; AND THOUGHT NOTHING OF IT. AFTER THE AIR DROP; APPROX 30 MINS LATER; SOCAL ASKED US TO CALL THE SUPVR AFTER LNDG; REGARDING THE KING AIR TFC. THE CTLR ADDED THAT HE THOUGHT WE SHOULD BE OK BECAUSE WE WERE OPERATING VFR AND DID NOT ENTER CLASS B AIRSPACE. THE SUPVR INFORMED US THAT THE KING AIR HAD TO ALTER HIS DSCNT TO AVOID US; AND THAT WE CAME WITHIN 100 FT OF EACH OTHER. EVEN THOUGH WE WERE UNDER A VERY HIGH WORKLOAD; I DON'T THINK THAT CONTRIBUTED TO THE INCIDENT. IT HAPPENED RIGHT AS WE WERE HANDED OFF; AND BY THE SOUND OF IT; EVEN IF WE HAD SEEN THE KING AIR; WE MAY STILL HAVE BEEN CLOSE TO IT. IF TWR HAD KNOWN ABOUT THE TFC; WE COULD HAVE BEEN LOOKING EARLIER; AND AVOIDED HIS KNOWN TRACK. THE BEST WAY TO PREVENT THIS WOULD HAVE BEEN TCASII. SUPPLEMENTAL INFO FROM ACN 466698: IF SOCAL HAD NOT ASKED US TO CALL THEM WE NEVER WOULD HAVE KNOWN WE CAME CLOSE TO TFC. THE KING AIR PLT SAID HE HAD TO MAKE EVASIVE MANEUVERING TO AVOID A MIDAIR COLLISION. WE WERE IN COM WITH SOCAL AND MONITORING BROWN TWR. NO TA'S/TFC ALERTS WERE GIVEN TO US THAT CONVEYED A SENSE OF URGENCY. FACTORS THAT COULD ATTRIBUTE TO THIS ARE A LACK OF RADAR COVERAGE/CTL NEAR SDM; HIGH CREW WORKLOAD; CREW FATIGUE; PHYSICAL CONSTRAINTS (BOTH PLTS WEARING HELMETS); EXTREMELY HIGH TFC VOLUME; DEPARTING INTO SETTING SUN; SMALL AIRSPACE TO WORK IN.