The SK 37 was the two-seat trainer version of the Saab 37 Viggen, used to convert pilots onto the type before they moved to operational squadrons. The rear instructor's seat, positioned higher and further back than the front cockpit, required Saab's engineers to raise the tailfin to preserve the aircraft's aerodynamics — and to fit a periscope, since the Viggen's steep nose-up landing attitude otherwise blocked the instructor's view of the runway. The type served at F15 as part of the wing's conversion to the Viggen from 1974 onward.

This aircraft, individual number 37805, originally served with F7 Skaraborg Wing, carrying the code "65". It's now preserved at F15 Flygmuseum in Söderhamn, alongside every other aircraft type that served with the wing across its history. Here it's displayed with its tailfin folded down — a feature built into the Viggen so it could fit inside lower hangars and workshops as part of Sweden's dispersed road-base defense concept.