It is my understanding that the 10th Mountain Division is the only unit authorized to wear the tab. They wear it for traditional reasons much like the 101st who still wears the "Airborne" tab.
I thought so too for many years. (My first unit was A 1/87 IN at Drum)
Years later, when leaving Iraq, My unit was replaced by the PA national guard. I think most of us have seen the "keystone" patch, There is a Infantry Company with these guys that wore the Mountain tab in conjunction with said patch, seems they really do train in mountain warfare.
I know of a NG BCT wearing a mountian tab. They are from the east coast. We called it the "jeigermister patch" because it had a big buck on it.
Ram's head course?Rams Head Course thru the NYANG?