Chuck said
Clarence, weren’t the #6 sights made in different heights?

  

Yes, but the basic design of one leaf with a big “V” notch & one with the triangle was the same as far back as 1902, & the patent is 1891!  Yankee’s sight having both leaves flat on top, without the triangle, resembles the special one made much later for the Model 54 & certain other modern guns.  None of my original Lyman catalogs between 1902 & 1941 shows any other type of #6 but the common one.