I just installed a LOK Sound decoder on my new ACe. Unlike past designs, the 2 metal frame halves are held together by the fuel tank and lower framing. No more screws and plastic nuts. I had to machine the frame on the rear end down with my Dremmel tool to fit my speaker. My only complaint is they have gone to a smaller thinner drive shaft and worm gear assembly, and the trucks snap into a thin somewhat ball joint. They flex alot and are quite flimsy and easy to know out of alignment. I guess that decision was made to made it look more prototypical. Anyway, with a few bugs fixed, she seems to run fine with my own modifications.