Over the past two weekends I have replaced my 10 year old Mermaid A/C. The unit was mounted under the aft dinette seat. The old unit came out easily. The new unit (an M-12 12,000 BTU unit) fit in exactly the same place, with the same bolts. Plumbing was the same too. The new electrical box is slightly larger, which necessiated placement of 90 degree elbows for the water in and out. I mounted the thermostat on the wall in the upper right hand corner of the wall separating the salon from the head and ran the wire along the starboard wiring chase. The vent will be replaced using parts available from Mermaid. Next Summer will be cool!