I know Knuckleheads were made between 1936 - 1947.
Is there anything visible on the Knucklehead in this photo that would pin point what year it was made...

 

The emblem on the tank are 40 to 46. Since it doesn't have the trim piece in front and rear of it. I would take it to be a 1940. The trim came out in 41.

 

1940 was the 1st year for that metal tank badge & the 1st year that they removed the old rectangular tool box from the right side.

The 1940 had the "pill shaped" tool box in approx. the same spot, but this one does not.

Additionally, beginning in 1941 and through 1946 that tank badge was accompanied by
horizontally mounted metal strips forward and aft of that badge.
Which again makes this a 1940 Knucklehead


The "Rocket-Style" Tip exhaust was introduced in 1941 and remained on the big-twins until 1949.
This bike has the older "Fishtail" exhaust tip/muffler which was introduced in 1934 and remained on the big-twins until 1940.


Therefore, I believe this is a 1940 Knucklehead with some later added stuff, like the handlebars, etc.


That air cleaner is very curious as well. Must be an aftermarket piece


Those "Beach Bars" were not common until post WWII.
like today customed to your liking

 

Well done john with a rather crappy photo. Has the seat parking lamps and bars tilted a bit down, not sure why but to each their own. Nice machine!!!!