For the Record: Straight Outta Supertest - What I forgot...
In the last batch with the description, I forgot a few tanks. Let's have a look at them...
Performance requirements for a new vehicle, intended to replace the M3 tank, were formulated in August 1940. However, development was started only in February 1941. The T6 used a number of mechanical components of the M3. A wooden prototype was built in June 1941. On September 2nd, 1941, trials were started. Eventually, the vehicle entered service under the designation the M4.
A 105-mm self-propelled gun on the basis of the M18. The order for the development of this vehicle was placed on August 31st, 1944. The Buick Motor Car Division manufactured a prototype at the beginning of 1945. However, development was discontinued when the war ended.
Development of this vehicle started in 1943, with 25 vehicles planned for production within a year. Two prototypes passed trials, but never saw action.
(SS: not sure what this is, some sort of T95 GMC evolution?)