Marker Light Qestion *LINK*

This question came up with regard to the SVRy, but pertains to all rr's in the early part of the 20th century. In the 1914 SVRy rule book, rule 19a requires a red lantern facing rear in the cupola and green facing to the front. This is apparently in addition to the usual marker lights required by rule 19. I have a 1916 Gen.Code of Op. Rules which also has rule 19 with regard to marker lights, but not rule 19a. Was this just an SVRy thing, or was it required on other rr's and how did they accomplish it? What type of lamp(s) would have been used? A freind of mine who is also a DRGW fan said that at one time the Grande had some sort of box on the roof of caboose cupola's for an additional light besides the usual corner mounted markers. This made me wonder if 19a was a rule that was in general application, but was eliminated, perhaps by 1916?
Any thougths or historical info on this would be appreciated.
By way of a little background as to how this question came up, the SVRy (Sumpter Valley Railroad Restoration Inc.) was recently given by donation an original caboose marker light that is a marked Adlake and is the left side. My neighbor a lamp collector has had the matching marked right for several years and agreed to sell it to us. These are the only 2 know to exist, though there must have been half a dozen sets at least during the hay days of operation. We are presently raising money through donation to purchase this lamp.(shameless plug) The question about the cupola lamp(s) came up as a result of us wanting to know what the correct lens arrangment was as the donated marker was missing a lens and the one we are purchasing has 3 green and 1 red. We found that based on the 1914 SVRy rule book, the 1916 Gen. Code and a later source that this was the correct arrangment of lens, though apparently some railroads deviated from this.