There is actually a lot your can do with your freehub. The question is, why are you wanting to replace it in the first place? If you need a new freehub body you can usually find an old hub to cannibalize http://www.ebay.com/itm/VINTAGE-BICY...item4ab081dd8c. Further, if you need new cogs they are also available. I have also used the 5 speed cluster of a 7 speed hyper glide cassette with the threaded lock cog. One difference is the Uniglide has symmetrical spines and the Hyperglide has one spline wider than the rest. Since the other splines are the same size as the Uniglide. You just need to file down about 2mm of the wider spline on the Hyperglide cassette and it will slide right on..