Some tanks during WW2 actually had radial aircraft engines. There are a couple technical repair manuals for the R-975 and this engine was built on the same line as the engine used for aircraft, in fact it's identical enough, I read an article a while back showing the FAA considers these engines legal for aircraft since they were aircraft built engines, even though they were installed in Sherman tanks. The RD-1820 engine was an R-1820 of B-17 fame but converted to diesel by Caterpillar and used in M6 tanks and i believe some M4 Shermans. There is also a Breeze starter cartridge manual which is the same system used on some aircraft during the war. Enjoy! Keith