Back in the late 1950s, the engineers at GMC had a problem. They had a good inline-6 for their commercial trucks and a few decent V8s to choose from, but the inlines-6 were more rugged and reliable than the powerful V8. So they did the only logical thing, which was the combine two inline-6 engines into a single V12 with a ginormous cast cylinder block and a 180 lb crankshaft. Hitting the scales at 1486 lbs, the Twin-6 V12 was a 702 cubic inch behemoth that made 565 ft-lbs of torque just off idle and a whopping 275 horsepower at 2400 rpm. It is, for better or worse, the most modern V12 ever built by GM…and I think I just found an engine for the next RX-8 I find with a busted Wankel, because this about the opposite you can ever get from a rotary without going to steam power. Where would you swap this 1960-1965 GMC Twin-6 702 V12 offered for $3500 in Palenville, NY via ebay?