this shows the port tank in a 1967 41tc, actual gallons is measured as 185.28. note the brown surface of the large cutout, it appears to be a fenalic material. The inside of the tanks did not show any deteroration and cleaned easily with a mixture of liquid tide and hot water. then was scrubbed with a little mop and rinsed with clear water until it was pumping out clean. After all the water was pumped out I dry mopped it until it could be air dried the rest of the way. I will use fiberglass to reinstall the plugs I cut out.