The Stovebolt Site Forums The Shop Area Engine Shop Difference between 38 and 39-4? 216 6 cyl??

Just bought a 38 1/2 ton. In looking at the various parts catalogs, I see there is a differentiation between engine parts for a 38 216 and a 39 through mid 40s 216. Aren't they the same engine? Why the split? Can someone please explain the difference to this newbie? Thanks!

1937-40 engines have very little different about them.
1937-39 used a four bolt flywheel, 1940-41 had six 3/8" bolts(1942 and later used six 7/16" bolts).
1940 was the first year for the kidney bean shaped oil distributor, held on with three screws.
1940 was the first to use a rear main seal.
1937-40 had dome pistons.
There were other subtle differences but that is a start.
Here is a list I have compiled with some of the differences.

Thanks Dave. Was wondering why different distributors speced in May catalogs for 38 and 39/40. I understand it may have had to do with the placement of the generator?