06 RM 250 Transmission compatibility- RM guru please advise

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.  

Can't do it suzuki changed the tranny in 04 -08 to k4,k5 models

Can't do it suzuki changed the tranny in 04 -08 to k4,k5 models

Have you tried? I understand they changed some parts, however If you are trying to swap all the parts I have been told that the cases will accept any year tranny 03-08. 

From what I remember from my 03

123 gear is different aswell as the shifter forks and drum @ the case is a little diff aswell

But I havnt tried to swap an entire tranny so It wouldn't hurt to try n if it doesn't work you can always resell the cases

And the k123 tranny is the same from 2000 to 03

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