I can definitely say that your engine is not a GT2. The 26GT2 comes with a MSR (ICU-L) ignition module. The MSR ignition module is designed to run with a MINIMUM of 6.5V. It will safely work between 6.5V to 8.4V and is self regulated for LiPol and LiIon batteries. They have a warning indication stating that this version DOES NOT have a battery test mode, therefore there is no need to place the engine at BDC before powering up the ignition since there is no pre-ignition spark to clear the cylinder. This new module also comes with an LED indicator to warn you when the ignition is in sleep mode (Auto-off), and when the battery is too low (<6 V).

The 26GT2 and the 35GT2 don't have the choke servo option, and the plug cap does not have the retaining set screw.

One thing is for sure, if you have only one magnet on your backplate you need an ignition module with a single pick-up designed for the generation 1 engine. Damroadhog is correct in that Horizon issued a bulleting stating that it was O.K. to use 6V, that is a 5 cell NiCd or NiMh pack NO LiPol/LiIon packs.

I think your LHS sold a bill of goods, and they should re-order the correct part for your engine.