I think down in the Schrade Collectors forum area you'll find a list of all known Uncle Henry models.
Generally though, Uncle Henry knives are characterized by stainless steel blades and "staglon" (aka plasti-stag, Delrin made to look like stag) handles. Overall build quality is on par with the Old Timer series, as in pretty good and very consistent.
As you probably know, the Imperial Schrade Corporation went out of business in 2004. Since then Uncle Henry and Old Timer knives have been imported from China for Taylor Brands, LLC. So if you want an original, be sure to look for the USA tang stamp.