My 'right' bulkhead (viewed from front of tank) is the emerg, with the center running wide open (no internal plumbing) and the 'left' bulkhead is plugged externally.
I used threaded bulkheads in the back box.
My back box allowed internal plumbing without interfering with the through bulkheads
I used threaded bulkheads in the back box.
My back box allowed internal plumbing without interfering with the through bulkheads