Cobra emblem hole? Help

[lodough780]

Let me start with the details from recent purchase. 1991 Marada 21 ft w/5.8 Omc cobra outdrive,also has king cobra exhaust system installed. I bought this boat in "non-running" condition to replace my 1986 Winner 17 ft w/3.0 mercruiser. Since then I have got the boat running and have rebuilt the carb. When starting it up with muffs I saw a large stream of water coming from the side of lower unit. Upon further investigation I have learned about this cobra emblem that was supposed to be there. Today I removed the lower unit in hopes of finding the back plate that holds the emblem on but it wasnt there. My question is how small is the nut or threaded plate and could it have passed on into the cooling system some time ago? Im assuminng The unit has been removed prior to me purchasing it since the u-joints have been replaced and the gaskets are fairly new.