The MKII and S35R have been used in Blimps. They are now usually used for stop frame animation, Time lapse or as VFX cameras as they are rock steady at 120 fps. Many are found on motion control rigs with BNCR or Panavision lens mounts. The GC (Goverment Camera) is the High Speed version of the Standard camera. Many of these cameras have been converted by Fries Engineering www.frieseng.com to R35's with a beam splitter or 35R3's with spinning mirror. The R35's can have virtually any mount (Nikon, Cannon, Leica , BNCR, Panavision) Accadamy or S35 Centered, but not PL. The 35R3 accepts PL lenses but has the focal plane shutter removed. (it cant be used for animation.) These cameras have been the camera of choice for VFX and motion control for the last 25 years before the Arri 435 came along. Many Visual effects films such as Star Wars , 5th Element, Titanic, Dante's Peek relied on these cameras.
Stephen Williams Cameraman
www.stephenw.com
(35R3 owner. My camera was used by Digital Domain on Titanic & Dante's Peek!)