Hi, Yes I saw the dimensions and never thought to check my Mercury S either, good point.
I dont see why the later concealed button underlever shouldnt fit most other later marks. The genuine pin for the catch is again available at the moment from Knibbs.Thats the bit I was stuck for and was about to make one. I have a spare push button new old stock underlever if you need one as well. I think the only limiting factor is where the catch pin fits, so maybe Mk5 onwards should fit without mods........ I hope! I'll let you know how I get on.