I'll try to dig it out of the garage tomorrow and take measurements and pictures.
It's acrylic and a pretty standard 3 chamber style. First chamber is return, which I filled with live rock. Baffles between first and second chambers. Second chamber I used for my skimmer. With creative placement, I could barely fit in my ASM G3. A sponge separates the second chamber from the return chamber. It's drilled for an external return pump and that's why it needs a new bulkhead. The valve fitting for my pump is glued and will have to be cut off in order to remove the bulkhead.