Albert Hardin, "The American Bayonet 1776 - 1964", states that the Winchester Repeating Arms added a magazine that could be loaded through a gate in the frame and some other refinements to the Henry Rifle to create the Model 1866 Winchester.  The front band of some of these arms are equipped with a bayonet stud on the right side to accept a saber bayonet.

Approximately 1000 Winchester Model 1866 Muskets were made to use a saber bayonet.  George Madis, Winchester author, statement unverified.

There are currently four types and five variations of which all are very similar to the Winchester M1873 bayonets.