Panzer IV turret profiles, as you can see if you just go by the turret it can be difficult to tell one from the other, at least with the F,G,H and J. Muzzle brakes can help with ID along with cupola styles, but as McCoy pointed out, even these (cupolas) could be swapped around. One difference between the F2 and the G, H, and J is the deletion of the vision port on the turret side.
