RE: 34 LRC Hull Construction??
The drain tube runs aft, across the fuel tank, exiting thru the transom. I'm still looking for the article, w/o much success, I'm afraid. I'll keep digging, tho'. Still not convinced it is a sag issue, as I have vertical 2x4 bracing tied into 2x4 cross bracing under the aft cabin edge. I do show some sag in the area of the engine room access hatches in the salon floor. Not much support there; but not much room for vertical bracing either. I have Detroit 8.2's as power. I suspect they are as big, perhaps even a bit wider, than your Cats. 27 years of being walked on would probably get anything to sag a bit. As long as I don't see cracking & wobbling, or the furniture stays level, I'm not going to be terribly worried about the way they built these boats.