Hi I know this is an old thread but i need some help with my Merc 18HP early 80's

The carb is a tillotson #bc2b carburetor.

Are you saying I can simply mount another carb on my motor?

Im having trouble with my current carb, seems to need rebuilding every year, ive stored properly. I cant find another one of these carbs as a replacment

any help woud be appreciated