Hi Graham
The mast and boom on our 36C are by Z spars so we fitted one of their rigid vangs. As far as I can remember the vang toggle at the base of the mast was already fitted as was the tang on the boom as these were the attachments for the original rope vang.
So it was basically a straight swop although the rigid vangs are supplied oversize so the the smaller tube did need shortening. Have a look at their online brochure but also suggest contacting them as they should be able to tell you exactly what you need. I have always found them very helpful in the past. The phone number I have is 01473 822130
Regards
Andrew