Agree^^^^^^^^^ I looked all over the net and could not find any info to support this. I am not sure on that. I found info of a stock swingarm length to be 18.25. Thats the best I could find. Did not specifi a year.
I have a '99-'02 service manual and a '05-'09 service manual and I can't find anything about the length of the swingarms. On the other hand, I did find that the overall length of the '99-'02 is listed as 72.2 inches and the overall length for the '05-'09 is listed as 71.7 inches. Whether the difference is in the length of the swingarm, I don't know.
Very possible, the 04/05 TRX450 has a shorter swingarm than the 06+ models. A bigger stance equals more stability. That is why most after market a arms don't only go wider but they push your wheels forward.
yes the old style 400ex's have a longer swingarm im not saying it wont work the just shortend it up on the newer ones. i knw this b/c i have a 06 and a 04 and my 04 is longer than the 06 when side by side.