muffler gasket

[usedtofish]

I have replaced the water pump on my F80TLRZ. I was about to reinstall the lower unit and noticed a boss that looked like it should have a gromet or some type of bushing on it. Looking at the parts diagram I see a muffler gasket that would fit the boss, I did not see one when i dropped the lower unit and from the picture I cant see how the bottom of the gasket would be supported or even seal.The picture could be poor and not show what it actually looks like and I am unsure if the part was there, what it sealed against or is needed. How often is a muffler gasket found not there?
Any insight is appreciated

[usedtofish]

I think I found the answer to my concern. I found a picture of the upper case on Ebay. The gasket seals the muffler to the upper case and the exhust dumps into the lower unit without a seal. So I am not missing a gasket that drpped off when I lowered the leg to access the water pump.
If someone knows there is a gasket for the bottom of the exhaust as it enters the lower unit please correct me.
Thanks in advance