M4 Sherman "The Right Tank for the Wrong War"

The_Chieftain:   I have not seen anything official on the matter either. My guess, proprietary rights. GM is not going to hand over the blueprints to its engine to Chrysler (and pay licensing fees) when they have their own perfectly servicable motor to put into things. Note that the P51 was created when North American suggested they didn't want to build the requested Curtis P40s. The Sherman design was owned by the Army, they didn't care who built it. It's also worth noting that not all engines were being built at the same time. As the Ford V8 phased in, the Chrysler multibank phased out, as did the radial.   There is another possibility. Part of the reason the Aussies went with the cloverleaf Cadillac in the AC1 was that the tooling required to start a motor production line for a new American engine wasn't going to be available for most of a year.