eagle tree guardian
 

how do you hook a eagle tree guardian to a glow fuel plane:)

I've installed them in electric and glow fuel planes. I can't think of any differences other than an on-board battery AND throttle servo connected directly to the receiver for glow where an electric plane gets its receiver power from the ESC throttle lead to the receiver. Guardian only cares about aileron, rudder, and elevator. The setup is quick and easy for glow and the same for electric.
If you want to know my opinion about R.O.I. and bang for your buck:
I've heard about 25 dollar units and 300 dollar units by other manufacturers and I'm not pushing eagle tree brand but it's the only unit I have tested and I have to give credit where is due. The guardian is really really good at 2D stabilization. If you're new to the hobby I urgently recommend it. If you're a geezer about to switch from your scale P-47 to a Rascal TRY THIS FIRST.

I have two of the first Guardians. They don't like vibration. Especially at the low rpm.
Test yours carefully before you fly it.