Polish and Bulgarian OOBs

[Pibwl]

As for Bulgaria, I've just found an article, that they modified MiG-17F to carry 4x 250 kg bombs (twice as many as unit 390) and used them from 1970 until 1986. Regular unit 390 was used at least until 1969 then.

Alternatively, at least 2 UB-16-57 rocket pods could have been carried (2x16 rockets ie. 2x weapon 186 4x57 mm rockets x 4)

399, 400 MiG-23 - should be attack MiG-23B variant, used no earlier than mid-1976 (now 1973)