I discovered that Tamiya was not so wrong finally, the prototype M51 turret was mounted on a A1 chassis with radial engine. I don’t know if the tank was operative, but the first pictures of the assembly line shows all cast A1 chassis with radial engine.

I had a lot of leftover parts from all my shermans I have been building since years and I decide to build this version, just bought the chassis, turret and barrel and all the other parts were from my spare box!

Still a lot for adding as well as all the electronics. I forgot to say that the gearboxes are cheap ( very) used HL modified to fit the Tamiya sprocket.