I have been in the market for an older Maple F50 and have found two recently ( a 1975 and a 1978) that have a walnut stain over the Maple. The sellers have assured me that this is a very rare finish hence increasing the asking price and value of the guitars but I was thinking if they were so rare how come I just found two for sale. Can anyone shed some light on just how rare is a walnut stained Maple F50 from the 70's and does it really increase the value of the guitar.