I'm pretty sure that speedo is a crimped-together unit. The glass is held to the speedometer cup by the ring which is crimped when installed. I say I'm pretty sure because that's the only type I've ever seen and by looking at the parts book it appears to be exactly the same. You might do a little research and find a shop which has the stuff to do it. The only one I've ever heard of doing it aftermarket, was a shop in England doing Smiths gauges on British bikes. They'd cut yours off and rebuild the gauge, crimp a new one on, for a price. Surely there's a similar business here in the states. There isn't a day that goes by where I don't find out something that's always been done a certain way is now being done a new way. Hopefully this will be one more thing.