Purchased a used Futaba(Conquest) radio and servo set for my SIG-LT40 kit, all seems to work just fine, question- what are the real differences in some of these servo's. I have a set of FP-S28'S and SP48'S, the weight seem's different like one has more windings than the others. I don't know, never took one apart for a look see. Hobby shop said they will work just fine, I would just like to know the difference. Is there a prescribed or adopted order in regard to which channel run's what on my reciever?. As a side note, when I install my remote tank filler should there be a check valve installed anywhere? like in the line to the muffler so fuel won't get accidently pumped in. Thank's for any input. Jerry