I am not famialiar with this boat, is it some sort of runabout?
FYI...
Yes - a fiberglass runabout.  The 1968-197x? fiberglass models were based on
the same design as the wooden Resorters (relatively flat bottom), so they
reflect a rather classic style.  I purchased this boat at the end of last
summer (first boat I've owned).  Last fall I gutted it and rebuilt the
wooden floor structure.  I'm now trying to wrap up the interior in hopes of
a July 4 launch.  For an early fiberglass Resorter the boat seems rather
unique, with the preferable navy blue color and a slight overkill of an
engine (18' / 427 Crusader).  At first sight I knew the boat would require a
lot of work.  When I heard it fire up and cross the water I pulled out my
checkbook.  My checkbook hasn't been closed since 
Here's a pic...
http://www.cuvantage.com/dougtemp/resorter.jpg
Thanks for the post, Rod.  You are correct, the negative lead on the ammeter
is indeed for a light.  I looked again at the gas tank this evening, and for
the life of me I can't figure out how it's grounded.  I think I'm going to
run two new dual-wire leads to the back.  One for the light, the other for
the gas tank (ground and sender unit).
Thanks Again -
Doug