I've got one pair of rack extensions for sale - best offer. I'll try to post photos later. These worked on an '08 ZFT3 tower - no idea what else they would fit. This is for the extensions only, not the clamping board racks. With the extensions attached, the standard MC clamping racks will hold most surfboards as well as most waterskis and wakeboards.
They are very simple to install. There is one allen head bolt on each clamping rack that you remove, then re-attach to the far end of the extension. There are three allen head bolts on the other end of the inside portion of the extension that attach to where the board rack used to be (two of the smaller allen head bolts are in place of the two pins on the clamping racks). Uninstalling these took me about 5 minutes and I'm a mechanical moron.
Buyer will pay shipping, which I'm guessing will be about $15.