From 1921 to 1939 or so, Dornoch was played as follows (and was called by JH Taylor as ("the finest course in Scotland"):
1st 5: Current 1, 2, 3, 4, 5
next 7: Current 6th tee to current 11th green, Current 12, 14, 15, 16, 17, 18
final 6: current Struie 1, 3(NLE), 4, 16, 17 18 (NLE)
Sometime in WWII the Struie holes 3 (NLE), 4 and 16 were taken over by the RAF and the current 13th hole was added to the Championship course, making it a 16 hole course for the duration of the War
In 1946 the 6th was rebuilt using the old 6th tee to the (new) current 6th green, and adding the Current 7th, 8th, 9th, 10th, and 11th (to the old 6th green). The WWII 13th was retained to make the course as it is today. The old 18th (a great uphill 210 yard hole from Littletown to the current putting green) was made NLE in the late 80's.
As one who has had the opportunity to play all the old holes (including those which are now NLE) in the 1980's, I can envisage the pre-1939 layout personally, and strongly think that the renovations to this great course were a significant improvement.