The Germans used a quadruple 20mm anti-aircraft gun on the Panzer IV chassis.
The new Roco Panzer IV Whirbelwind has a pin in the center of the chassis and the turret revolves around that pin.
By happy coincidence the pin made on the Panzer III hull from the Panzer III 75mm short gun is the same size as the hole in the Panzer IV Whirbelwind turret. In 1944 the Stug units based on the Panzer III automotive parts wanted anti-aircraft protection on the Panzer III chassis. That way the repair parts would be the same for the assault guns and anti-aircraft guns. The turret ring was smaller on the Panzer III than the Panzer IV but there is good evidence that they did manage to make a few Whirbelwind Panzer III anti-aircraft tanks. They modified the turrets and custom fit them on rehabilitated Panzer III tanks.