Ford historian Jim Wagner sent me a photo of a 1942 G8T. It's included here. It has the 6-stud wheels, as Hanno pointed out the G8T should have, since it's more militarized than the 2G8T. The date on the photo is 10-20-1942, showing it was already in production in 1942, in addition to 1943 and 1944 (and 1945??).
http://www.mediafire.com/imgbnc.php/...b428df8f5g.jpg