You can always make your own calibrated stick. I did for the two speeder, but a three and a half gallon tank contents is pretty easy to put in cans and replace with a measuring jug, marking the stick as one goes.
I expect the fuel tanks on the old 3 Wheelers were similar to that of the Seven - a rectangular box with a screw-cap on top. Alas, things are not so simple with the modern 3 Wheeler...
[Edit] You beat me to it, Jays!
