That was actually what I was wondering myself. Whats the difference between a trainer and a plane like the extra 300s? (Aside from $300 and about $1000) I did look around for this on the forum, but I couldn't find anything. I did some research and I'm planning on building up a Great Planes PT40 MKII. Can I use the radio and some of the servo's on this model, the radio is a futaba r148dp and there are at least 5 servo's that are futaba 3305's. Any help is greatly appreciated. Thanks