Wow, can't believe i came across this forum. I've tried in the past searching for ANY info on these models and came up with nothing. I have the Chrome/Olive Military P-51 with an OS46FX and the 40 size retracts and added scale flaps. I've had it for ten years and it's one of my favorites. The plastic skin on the top of the fuselage is warped from hot days and i had to make a whole new front cowl after a tough landing but she still does great and is fly ready.