Note: I learned about this from a Tweet by the Kerouac Project, which I recommend following if you are a Twit (Tweeter? Tweeterer?).
The original manuscript for The Dharma Bums is now at Rollins College in Winter Park, Florida. Clicking here will take you to a blog post about it, including pictures of actual pages and some interesting tidbits of interest to Kerouac fans.
Apparently, Jack had typed the novel on teletype paper just like On The Road, but that scroll's whereabouts is unknown, having been sold to an anonymous buyer by Christie's in April 2003.
The manuscript at Rollins College is a version Jack typed from the scroll - there's a picture in the above blog post of him doing so.
I'd love to see the manuscript, as Bums is probably my favorite Kerouac novel. You can tell by my license plate.