its 6AK09 so then its September ??
Thanks
Likely September 1940. This would fit with my observation that only trucks built in the first few months of the 1941 model year have the slotted interior screws.
Those slotted screws are not like something you could get at a hardware store (their tips are reduced in diameter and unthreaded) and I have seen the exact same type on a handful of different quite original 1940 and 1941 trucks, so I do not think that they were replaced wholesale later in life.
