Need help. Extra dowel pin with o-ring

[Gotme1]

Getting my 03 400ex motor back together and I have an extra dowel pin with an o ring around it. I've been using the manual and even looked back through it and didnt see any thing about this dowel pin. If anyone has a pretty good recollection of the inside of a 400 motor, could you please help me identify where this goes? Thanks

http://i679.photobucket.com/albums/vv160/anteekyle/7ddbf98e.jpg

[Stickman400]

That goes on one of the oil lines that goes into the engine from the oil tank and up to the cooler. Right side of the engine.

EDIT: You are showing 20 and 18. It goes on the end of either 2 or 3.
http://www.motosport.com/atv/oem-parts/HONDA/2005/TRX400EX/OIL-COOLER

[Gotme1]

Thanks alot man.

[Stickman400]

No problem, I'm here to help.