Need new hull, turret, and gun. Fireflys used 75mm Turret and M4 (early hatch), M4 Hybrid Hull, and M4A4 Lower hull variants. Later US Variants, (never fielded) had HVSS and M4A3 hulls. You could use the Mato hull to start a Hybrid hull, but you still need a 75mm Tamiya turret and the correct rotor shield and mantlet. This is all Rivet counter stuff but the parts are available.