Neil, Sounds about like what I have on my 1980 M-15, of course without ratchet block and 30 years of wear. Another difference is that I can adjust the angle (to a point) from block to cam cleat. I would imagine it is original equipment, and it works well. I use my foot to lock it and an upward flip to let it out when I get scared, which is often. Here is a photo: http://thorsett.net/images/ swivel_block_cam_cleat.jpg Jeff Thorsett M-15 #102 "Scamp"