When I took my leg off the gasket was bedded in a black sealant. Any Idea what type it may be? The same stuff was around the hydraulic lines for the trim tabs. It is still a little flexible.
Here is the best pic I have.
It is probably a polysulfide. Before you reinstall your leg scrape all of that off and replace with a factory gasket and their recommended sealant. If nothing else don't use 3M 5200 - you'll never remove it.
There are several types of sealants, adhesives on the market. All will have their respective uses. Here's a good link to look through :http://www.boatus.com/boattech/casey/35.htm