Here's the ski-post they're talking about...I had it on my '74 and the 21...it worked well for years for wake-boards and tubes...I liked it because it was removable when it was fishin' time...
http://www.overtons.com/modperl/prod...n&merchID=4005
You can barely see it in the photo below...it mounted higher in the 21 because I was able to base it on the front wall of the splashwell...mount it the higher the better...