The answer will depend on your gauge set, what it was supplied with and where you're mounting it - ideally the temperature sensor should go directly before the water outlet, which on a Samurai is in the intake manifold - are there any threaded holes near where the original sender fits that you can use?
Some people fit the sensor in a short piece of pipe spliced into the hose, but this will not show the engine temperature until the thermostat has opened, and if the thermostat fails shut, the engine will overheat before the gauge moves from cold.
I have no "adapter" on my oil pressure gauge - your's was probably supplied with a 1/8 NPT fitting, Suzuki (and many Japanese manufacturers) use 1/8 BSPT, which is what I am using.
