Here's my take on the three sub-groups of the never completed destroyers for the Regia Marina. They were large destroyers (120m) armed with 4-5x135mm guns. The AA battery changed from the 1st and 2dn group. The 1st had all single 37mm Italian mounts, and the second and third group would have features quad 37mm Italian mounts and German 20mm Flakvierling. The third group further differed in having an alternating engine-boiler room setup, as opposed to all boiler rooms in one area and then the engine rooms behind.
First Series:
Second Series:
Third Series: