Here's a saddle titled "1850's Hope Saddle" but certain aspects of it looks very much like the earlier 33 Grimsley Dragoon saddle. The stirrups are quite obviously later replacements. The iron ring on the rear bars, is typical of military attachments....either for saddle bags or possibly a crupper. Grimsley would later employ several of the same aspects to the '46 Grimsley Dragoon saddle that would last up and slightly beyond the Civil War.
If this a '33 model then it may well be the only survivor in existence. Probably in most cases, those saddles that survived the riggers of military life, were sold off to civilians who used them up...or refitted them with new riggings, stirrup leathers, skirts, etc...or in other words, if the rawhide covered tree lasted, eventually the saddle would look little like the original military saddle............the difference between the McClellan and the '33 built on a "Mexican" tree............no mistaken the McClellan, even with the addition of a brass horn on the "Mule model" McClellan.