Can I swap the entire transmission from an 06 RM 250 into 03 cases? After hours of research, it seems that I should be able to swap the entire transmission into the 03, all the driven gears have the same part numbers and the 4 and 5th drive gears have the same part numbers. I am thinking they beefed up 1st 2nd and 3rd gear which explains the difference in part number for 06 but I just want to know if the entire 06 transmission will fit into the 03 cases. The only real difference I can see in the cases are the 03/04 use different crank main bearings and right side seal then the 05/06. I just lost the motor in my 06 (rod went through the cylinder and cases) I got an 03 motor but I want to swap my 06 tranny because it only has 15 hours on it. Please confirm if I'm correct in my research.