It has a 1 1/8" steerer tube and as long as the ID is constant and proper (sorry don't know the proper ID off the top of my head) you can use a 1-1/8" quill. There are 1 1/8" quill MTB stems but I dunno if that's what you're after exactly. Some of them are impossible to get drop bars into, but some will accept them.

http://www.ebay.com/sch/i.html?_trks...quill&_sacat=0

http://www.universalcycles.com/shopp...ls.php?id=7466