Thanks VF19_Congo + Koty.
I used a different setup, but those who wanna try this, make sure to backup the files you replace.
Stationary
MIG_21PF vehicles.planes.MiG21Static$MIG21PF 1
MIG_21PFM vehicles.planes.MiG21Static$MIG21PFM 1
MIG_21FL vehicles.planes.MiG21Static$MIG21FL 1
MIG_21S vehicles.planes.MiG21Static$MIG_21S 1
MIG_21MF vehicles.planes.MiG21Static$MIG_21MF 1
MIG_21bis vehicles.planes.MiG21Static$MIG_21bis 1
tech.
//===================================================================
//===================================================================
[MIG21PF]
Description MIG_21PF
Icon Plane
Class air.MIG21PF
PanzerBodyFront 0.008
[MIG21PFM]
Description MIG_21PFM
Icon Plane
Class air.MIG21PFM
PanzerBodyFront 0.008
[MIG21FL]
Description MIG_21FL
Icon Plane
Class air.MIG21FL
PanzerBodyFront 0.008
[MIG_21S]
Description MIG_21S
Icon Plane
Class air.MIG_21S
PanzerBodyFront 0.008
[MIG21_MF]
Description MIG_21MF
Icon Plane
Class air.MIG_21MF
PanzerBodyFront 0.008
[MIG_21bis]
Description MIG_21bis
Icon Plane
Class air.MIG_21bis
PanzerBodyFront 0.008
//===================================================================
// eof
My list includes all initial Mig-21 versions from both the 2nd and 3rd Gen packs.