The original 1935 bellhousing was attached to a 206.8 CID engine and would not fit on a 216 or a 235/261. The bellhousing presently in the truck probably came from a late thirties/early forties truck if you don't have a 206 engine. As red58 said, the bellhousing doesn't determine the drive line, the output of the transmission does. On ton and a half trucks, the rearend became open drive in mid 1940, but it still had torque tube from the transmission to the carrier bearing (split drive line).
A 206 engine will have a wider spacing between no. 3 and no. 4 spark plugs than between the other plugs; the 216-up engines had even plug spacing.
