Mike: I also have a MK1 and did a Tides Track two years ago and have been very happy with it. Makes getting the main up much easier - however I plan to drop my mast this fall and replace the masthead sheaves with the newer bearing type. Any way, here are the specs I submitted with my order. Slot width - K; Lip thickness - 4; top to bottom of sailtrack groove - 41' 5"; Length of existing mast gate - 3"; top of gooseneck to bottom of mast gate - 4". My gooseneck was raised about 4" by the PO - I think to clear the dodger/bimini with the boom, so I didn't meet that clearance spec. But I removed the gooseneck and fitting to install the track and it went smoothly. I did file the inner edge of the top of the mast gate some to allow the track to slide in easier too. Ordered my track through Sailnet as they offered a discount at the time. Hope this helps. :)

My boat is a tall rig and the mast is not painted. Could make a difference. I do remember though that the guaging was a little iffy? When I tried the smaller pegs - they would enter the slot but felt like I was bending them a little and I was afraid to get the track to tight as it might be a chore to install. As it turned out the larger size worked fine though the track does want to slide down to the gooseneck. I plan to put in a spacer this spring and retighten the toggle at the gate. I did all the fitting - took a little time but worked fine. I used a hot ice pick to melt the holes for the batten car screws and the rest were all just pins through the webbing straps.