I can now answer my own question about which retract brand to get. I'd have to recommend the top RC. The Robart has this strut guide sticking out the side you'd normally put the landing gear door on and that way isn't going to work. I think the strut can be flipped over and fit in the landing gear well. But the other annoying thing is one of the two main retracts stalls out very quickly and it never fully traversed a up or down without help. It has to be replaced.