Why are there a lot of left side only rearsets on ebay? Is there some reason why just a shift side benefits as much as both sides or something? Or is it the fact that most of those are unadjustable or standard shift type only (1 down 5 up) and racers are changing to track type which I believe are 5 down, 1 up?

 

Maybe they are selling the gp style like you said 1up and five down. GP shift kit is normally sold as an add on to the sets that you already have.
Most seem to be sold in pairs; I would not want different lft and rts, which just does not make sense.

Which one are you looking at?

 

These:

http://cgi.ebay.com/ebaymotors/ws/eB...3AUS%3A112&id=

 

It is stock stuff, guy could be telling the truth or it is off a totaled bike and the rt side was damaged, came off a stolen bike and the lft side is already sold.

Try these puppies, I want so bad. http://www.attackperformance.com/