Unfortunately the odds of getting a match are pretty remote
. It is more than frequency that must match without getting into a bunch of technical details.
hulls from the 1960's tend to be very thick because back then fiberglass was a relatively new hull material. Builders back then overbuilt by today's standards because they did not have as much experience with the material as we have now.
Probably the best thing to do is to wait for your next haul out
, remove the old transducer and replace it with a new transducer. Thick hulls like yours will attenuate the signal and although it may work in shallow water
, it may not work in deeper water
. Newer transducers also have options you might want such as a paddle wheel
(dubious accuracy in almost all cases), wider cone angles for boats that heel, dual frequency (200kHz/50kHz) or a temperature gauge. You can also choose between bronze or plastic, which is less expensive.