So I checked the code on the block, it says K590I4II , I'll start digging into what that can mean
although that is a number someone stamped into the block, it might not be the casting number... the stamping letters are rather crooked there. I'll keep digging and try to find some more numbers on there.
Where would someone find a crank replacement in lets say a 206? are these things still available or by some miracle made by aftermarket?
Engine Serial number K590I4II is a good number for a Commercial (1/2 ton) 1936 206.
'K' Prefix = Commercial
5901411 = unit number starting with 5500179 and ending with 6784512.
You engine was built in January 1936.
Your Block casting number will be 836010. Your head will be casting number should be 837981.
Cranks and Cams for the 206 haven't been made for over 60 years, you need to post 'wanted' ads everywhere you can on the web and keep an eye on eBay and CL, and hope you get lucky! The p/n for the Crank is 837630 and it's Forge Number is 837631.