Hmm...5ver hitch rails are standard but placement is not??

Thanks for the comments. I was adjusting hitch height to level out trailer when I noticed king pin position in relation to axle. Agree with all your comments about chucking. I have a thread going here http://forums.woodalls.com/index.cfm/fuseaction/thread/tid/28930417.cfm
to get help with my chucking issue. I was mostly interested in why the industry would have so many different locations for placement of the rails for the same vehicle.