Hey Fellas, I too bought a 450F ,an '04, and absolutely loved the motor, handling, everything about it except the 4 spd. tranny. I was at the point I was going to sell it and wait for Yamaha to get off their collective behinds and do the right thing...offer a WR 5 speed in the razor edged YZ package. At the Desert Mountain Enduro this spring, I spoke with Ty Davis about how he dealt with the CR 4spd in his 450. He smiled and told me the '04 WR tranny was a drop in replacement. I asked if he had any durability issues with the WR tranny. His response was if you run a stock motor, there will be no issues with the 5 speed. He said his motor was strong enough to pull the KX 500s on top speed...and he had no issues with the tranny..yet. This was his 3rd race on the tranny and his mechanic would be pulling it apart for a routine inspection. Armed with this information, I stepped up to the plate and ordered a complete WR tranny, lock, stock and barrel...it is indeed a drop in fit. I test rode it this weekend, and it is the answer to what we have been clamoring for for the past several years. I can slog along and jump around in watermelon sized rocks, drop into a sandwash, and loaf along at 65-70 mph no problem. Why did we have to spend extra cash to do what Yamaha could have done in the first place? Don't care now...mine is "fixed". Cost was a little over 600.00....well spent. Anyone need a used 4 speed?