Call Catalina Yachts in Florida at the plant and ask for Warren Pandy. Tell him Crazy referred you to him as his nickname is Skip or I called him Skippy Peanut Butter.
Catalina has the exclusive rights to the mast section for the 18. The manufacturuing plant in California is now closed. So go direct.
As for Dwyer, you would have to put a new mast step on, new rigging and so forth. Skip at Catalina is a charm to work with. I hope this helps. If not, call Ron Frisosky at 941-914-3890 and he can direct you to the right source. I use to be a small boat catalina dealer for many years and catalina built all their own small masts to inlclude the 18.
crazy dave