Actually, the turret on the calliope was a fully functional gun, they just added rocket racks for quick deploy arty in battle, was not very accurate in any sense of the word. The Croc on the other hand had only the flame system, the ammo storage area was replaced with a fuel storage container and reinforced armor and hull around it. They tended to "pop" when hit.
what a horrible job driving one of those would have been...
