They have a 1" steerer, but I also have a set of XC51's with an 1 1/8" steerer which is interchangeable. Buy one get one free! The XC51's aren't in the best condition, but the XC600's work great £45 posted for both sets of forks.
Now a see that you are also offering a XC600.
I thought that the XC600's onlt where in gray with a bit of blue. I'm actualy looking for that kind of colour. But I keep your offer in mind.
Pretty sure I've got a pair of 600's in metalic red the finish is virually spotless the only cosmetic difference from new is the transfers being a bit faded, send me a PM if you're still on the hunt.