I thought as much when I inspected my XT, though I suspected they'd use some sort of 'weld' to stop folk having a prod about.
Thanks for clarifying...
If your XT is the M785 then the caliper is identical to the SLX above (except painted a different colour and with those magic letters 'XT'). There's nothing other than two bolts holding the two halves together. The long bolt in the picture goes through the top hole (in the top picture), and the banjo bolt which attaches the hose to the caliper goes through the bottom one. The banjo bolt has the 'O' ring pictured to seal the two halves (note the recess for it), but the top one doesn't even need that as there's no oil around it.
Very simple to take apart, just make sure you force the pistons out as far as you can while its still attached to the lever, as they're a bu@@er to get out otherwise (learnt the hard way ) Re-assembly is even easier, but needs a good bleed to get air out of the small oil passages drilled through the caliper body (see bottom picture - the passage on the left goes to the bleed nipple, and the one on the right to the banjo bolt).