We recently purchased 1986 M 43 CC, and now find less diesel tankage than advertised. Does anyone know if the 75 gallon fiberglass water tank under the sole at the base of the companionway can be safely converted to diesel? It has already been contaminated with diesel by previous owner, and we expected 135 gallons of diesel tankage rather than only the 60 gallons under the port settee. I understand that if the fliberglass resin used is compatible, then it would accept diesel. If not there may be a risk of diesel dissolving the tank and eventually leaking. The boat was advertised as 125 gallons water and 135 for diesel, totaling 260 gallons. However sailboatdata.com lists 200 gallons water and only 60 for diesel, which adds up to the same amount and suggests the 75 gallon tank under the sole was intended for water. How can we determine if this fiberglass is compatible with diesel, or has anyone else done this in similar or same Morgan? I appreciate any advice.