My '42 1 1/2 ton ex fire truck was originally for a Naval Base in WWII, it has a 216 (that I believe is original). I guess, beings that it was a pumper truck, would technically make it an ex fire engine versus a fire truck. Regardless, I'm pretty sure that it is a 216.
I think back during the war, they weren't all that picky in some instances regarding engine size.
John