Hi,
Dont have one, but i bought this for mine:
savemybug.com
It connects to the original oil light, and will flash when temp too hot, when you look at the unit on the engine, you will see where the metal rod moves in a arc, it will eventually make contact at the top once the engine has got too hot, simples. Mine runs at about the 9 o clock posistion if you look at my pics, and on the long drag up Porlock Hill, which is a steep 25%, in first gear, loaded up westy, mine went up to maybe 10-11 o clock, so hot, but not overheated. As you approach too hot, it will flicker, before eventually staying on, you could of course rig up a bright LED like a shift light for examle to make it easier to see.
Some pictures in my gallery, the last few pages iirc.
Cheers!
Alistair