68mm perhaps? The m952 works on both 68 & 73mm shells with a couple of 2.5mm spacers (same as HTII spacers so easy & cheap to get). If you've got a 28.6mm downtube chances are you'll get away with the shorter 112.5mm, fatter 34.9mm tube (usually on ally frames) will probably need the longer 116mm axle.
If it's a 31.8 tube then pick one and cross your fingers...
ill try and measure the axle of whats in there.... It prob is 68mm I was trying to measure while it was hangingon the wall and trying not to fall over the patio furniture!