Fuel sending unit or Gauge most likely to fail?

Hey all,

My 97's fuel gauge has gone bonkers. Sometimes it reads a full tank, sometimes
3/4, but it's never accurate. A few months ago it started working
intermittently, but when it did work, it was accurate. Now it just doesn't work
at all. Sometimes it moves from full, but only by a hair, no matter how much is
in the tank. I know I need to fill up after 300 miles, so I'm not worried about
running out of gas, but I'd just like to fix it. Does anybody know which is
more likely to fail, the sending unit in the tank or the gauge itself? I don't
want to have to order a whole new gauge cluster if I don't need it, and on the
other hand, I don't want to take down the gas tank if I don't have to. Anybody
have any way to test and see which is my problem? I haven't cruised the garage
at Miata.net yet, but I doubt this is in there. Thanks for any help!


Paco

97 Montego Blue Miata
91 Toyota Previa
77 Suzuki RE5