That is the turret from the old Peddinghaus 1A5 conversion. It is supposed to be the most accurate version of the Leopard cast turret and was produced as a conversion for the Italeri/Testors 1A4 kit when there were no 1A5 kits available.
I'm saving it for another Leopard and I assume that the C2 conversion was built for the Revell turret so the fit would be questionable. Mainly used it for a guide to the shape and location of the mount points.
Paul