Now available in the American Cold War folder of the Dropbox, the MBT-70/Kpz-70 was an American-German joint project prototype, featuring many pieces of interesting technology. It uses the American 152mm Gun-Launcher hybrid, capable of firing APFSDS, HEAT and ATGMs; and packs a 20mm autocannon for the commander. Germany eventually pulled out of the project due to cost overruns, and the US developed it into the XM803.
Watch the showcase video on the qarsan channel for more info and to see it in action.