The Sonic Tronics units are pretty simple. i had a Hawker Typhoon stunt model that was built by Walt Brownell, and he had something that was even more simple, but I have no ide where he got it. He had the side mounter plug in mounted on the side of the model, and one wire had just a small, round closed connector that went under the head of an engine mounting bolt and flat washer. The other wire was attached to simple clip clip that looked like a hitch pin and attach to the post on the glow plug. Might have been a store bought item or Walt could have made it himself. I think that if you have some old glow igniter chargers laying around, you can use the end off of one of those to attach your driver to, you just need to make some sort of mount for it. You then attach the round connecter and the clip to the other end of the wires, and you are ready to go. Also check the R/C car market for remote glow plug hook ups. Some of the engines on truck and buggies are available separate and are very simple also.
Type at you later,
Dan McEntee