Looks like an M2A2 or A3.

(In GuP, it would probably only qualify for use in Ribbon no Musha’s Tankathalon <=10-ton fights.)

Oh look, it is the Mae West tank.

This could also be the a Polish Vickers E. They all were derived of the Vickers 6-ton tank and are primarily distinguishable by their rear. After viewing other relevant GuP pictures, I think it's probably really a 7TP.