From the pics I have seen on line, the 615 has 3 rods that link the base to the tank, similar to the sticks inside a teepee. These 3 rods are the skeleton supporting the tank. If this is a 615 tank, how would the 3 rods attach to the tank bottom? The 2 pics I will attach to this reply show the 3 rods, but I cant find any better pics that show the rods interacting with the tank base.
I was gifted this pump from my brother in-law, and unfortunately, I have no internals to work with. No piping, no rods, just a blank space in-between the two base skins. I can make what is needed, just need a blueprint to work from.