If that's your rear cylinder it takes a different/smaller one. That one fits into the head like in front but not the header in the rear. Most sellers are either unaware or unconcerned. I did find a set that included everything I needed and more but I'm not sure where. I think it may have been some Europeans on E-bay. 

RIGHT YOU ARE! I found this out today when I finally went to the front cylinder and the gasket fit right in. Sadly, I will have to go to the dealer and pay 3 X what I paid for the pair jus to buy the one!

THANKS EVERYONE!!

That's what I told you in a earlier post. Glad you figured it out.