I was doing some searching and I found this on mytractorforum.com under HG stuff. 
( &quot;It has Cletrac written all over it because of the color Orange was used on HG from 1939-1944. The Factory color from 1945 to 1950 (Oliver built) was green. In 1951 it went Yellow. 
 
But you could still order your new tractor during in 1945-1951 with Cletrac orange, construction yellow, or Oliver Green. Same goes for post 1951's- you could still order the green after they went to all yellow.&quot; ) 

I found the second paragraph interesting and was wondering if this was true?