RE: Need to know what to pick up or order..
I expect you are pretty much stuck with gh 15 since you can't change the tx crystal without sending it in for tuning. Besides it's illeagle to modify the tx unless you are a licenced technition. I would just send to Radical RC and get a channel 15 for your rx . You can change these yourself as long as you stay on the same range[low band, high band, etc.]