I don't think that is a G, certainly not in the style of the 1945 G. I think it is a 6 as in 1946, the style is much closer. 1944 was a E for emergency, 1945 was a G for Government.
We had the date code chart posted on this board, in a sticky, but I cannot find it, so here it is again.
The breaker bar has a 5 with rounded top and bottom, that is 1955.
Charles