I hate to dump on your first post here, but really, you have not made your quest very clear at all. I've been around boats for a long time, and I've never heard of a whitcraft coastal cruiser, nor am I at all sure what the hell you mean by a "fitting for the upper deck
If you really want help here, you must give us a LOT more info. Photos are helpful, as well as using more precise wording. You will find that CFers are a very helpful lot, but we can't work in a vacuum.
Please try again.