Throughout WWII, many prototype tanks never made it to the battlefield but the innovations developed during their gestation did make it in to production as refinements to existing designs.  Case in point is the T-23 prototype that was a radical innovation with heavier armor, electric drive, new turret, and 76mm high velocity gun.  The T23 turret was adapted to the Sherman tank and the lower hull eventually became the Pershing.  It was even a test bed for the HVSS suspension.  I ask, what if?  I will build the T-23E4 derivative as if on combat trials just to have a vehicle no one else has.  There are drawings of this type in Honneycutt’s Pershing book and that is enough of a validation for me.  T-23 may have never seen combat bit it was a crucial link in the evolution of later US battle tanks.