NEW
OLD
It's my opinion that 1939 and 1940 were definitely gold. 1941 was blue. 1942 (???), 1944 and 1945 were definitely yellow. The helmets in the Cleveland papers for 39 and 40 had a shiny appearance. So I would go with gold for those two seasons. The helmets after the 1943 layoff were yellow. The youtube newsreel from the 1944 game at the Bears would indicate a definite yellow as does the 1945 NFL Title Game newsreel as well as pics from the Plain Dealer.
So:
1939 gold
1940 gold
1941 blue
1942 gold (but NOT definite)
1944 yellow
1945 yellow