Have read CLASHES by Mitchel several times, AWESOME BOOK. I have a stack of Osprey booklets (some better than others) on the Units and Duels of the conflict, even struggled through Boniface's MiG's over Vietnam.... Some questions 1. Did the PVAF ever use Heat Seeking missiles from their MiG-17s? Every now and then I hear something....wondering if HS missiles on PVAF 'some' or 'later' MiG-17s is urban myth. Maybe I'm thinking of Middle East MiG-17 upgrade. Any help appreciated. 2. Noted the MiG-21F-13 carried only one onboard cannon, gave up the second cannon for HS Missile equipment. I know the MiG-21MF came with the belly cannon. Is there any solid evidence that the GP-9 recessed gun pack option was used by the PVAF on the few PF or numerous PFM versions in their inventory? 3. I recall the Earlier MiG-21s were limited to 600kt below 12k ft due to fuel pump issues. I understand this was fixed in the MiG-21MF. Any info contrary to this? Am recovering from a heart attack and bypass surgery roughly a month ago...dusted off some books and started looking at my substantial aircraft miniatures RAIDEN MINIATURES to release the F-105 that I did the master for, also an RB-66.