Re: NNG, but D&RGW 4-6-0

The earlier photo with the high mounted headlamp was in 1926. The later photo with the headlamp mounted in the center of the smokebox door was from 1942.
As stated by others, early on when 760 was built, most of the locomotives were built that way, but later steam locomotives for the D&RGW were built with headlamp in center of the smokebox door.

I can't comment on how many 10 Wheelers were changed in this way, but as for 760 specifically, I think the words from a "They Might Be Giants" song seem appropriate.
"Why'd they change it I can't say.... I guess they liked it better that way."