[CaptainHaplo]

Air wise I would drop the B2.

If your looking for a total of 11 combat units from that timeframe - use 2 from each "side" (Nato/Warsaw) on both land, air and sea.

That will give you 12 - and then you eliminate the least impactful one of them all

Nato Air - Early period would either be the GR7 or Mirage III.
Late would be the F/A 18 E/F or the F-15 E

Warsaw Air - Early period has to be the Mig21 Fishbed.
Late period would be a tossup - Mig 29/Su-27/Su-35

Nato Land - Early would be either the M60 Patton or the M113.
Late would be the Challenger II (if the timeline was a little longer - the Merkava would take it)

Warsaw Land - Early is the T-64 without question.
Late should be the BRT-80/90 (the T is outside the date range, sadly)

Nato Sea - Early - CVN-65. 'Nuff said
Late - 688 / 688I

Warsaw Sea - Early - Either the Project 627 (November) or the Kirov
Late - Has to be the Akula

Least "impactful" would be the Warsaw Pact late air.... I would drop that to get to 11 total.
I can give specifics on why each one makes the cut. If your looking for 11 from "Each" category, then its another question entirely.