The Jet parallel clamp works with the Bessey K-Body Extender. Here are links to two threads I started. I only have Jet parallel clamps, but have used most of the other brands. I think that the Jet is by far the best clamp. Some of the other clamps may have more clamping pressure, but the Jets have more than enough clamping power for any glue up. If you cant bring your joints together with the Jets, you did something wrong.
http://www.sawmillcreek.org/showthread.php?t=67765
http://www.forums.woodnet.net/ubbthr...v=#Post3320241