A cruise-o-matic is a variation on the old f/m3, but has a valve body to allow the car to automatically start out in 1st gear. The trans housing is cast iron with a removable cast iron bell housing (converter cover). The shift points are controlled by a throttle pressure regulator. That is why the adjustable linckages at the bellcrank. This transmission was later adapted to use a vacuum modulator to control shift points and was used thru 1977. A c6 is a completely different animal. The c6 is and all aluminum housing with the bell housing cast as part of the housing (non removable). Due to the non removeable housing, there are various cases that were used to bolt up to different engine series. (fe, small block, 429/460, navistar diesel, etc.) the c6 is a very heavy duty transmission and was usually used in heavy vehicles such as full size or high-performance cars and wagons, trucks and vans up thru 1-ton. The c6 was produced from 1966 thru 1991. Carbureators on c6 vehicles have the extra lever to attach the kickdown rod. Hope this helps.
Bill