update
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After a bit more digging, and to confirm the learned observations above, it seems the Swiss Air Force got their two-seaters with Mk 4 seats (and 200 Series Avons) The single seaters had the original Mk 2 or Mk 3 seats, but with the 80 ft/sec gun, giving them the same ground level and 90 kts capability. I suspect the difference was the date of original manufacture of the airframe or the later new- or re-build as two seater.
The Swiss Air Force did not put rocket seats in their Hunters. Entirely separately, it appears Martin Baker said twenty years ago, that doing the job would be quite easy, but the R&D (and presumably approval) would be very expensive.
The Martin Baker Mk 2, 3 and 4 seats normally had two separate harnesses - one for the parachute, the other for the seat - both permanently secured to the seat.
The Swiss had their seats modified to take an American parachute and harness. I believe this is the torso harness with three connectors, two thigh and one chest, which you don before flight and walk around in. Apparently it is time consuming and difficult to put on, and it was not designed to accommodate a maewest. Thus it might have been tricky to find and release the chest connector under the inflated mae west, when in the water. ...
LFH
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