Yet another Flathead ID problem

I have a '40 Tudor with a 59 block with crab distributor. Am I to assume it is '46 to '48?
Some literature I have read doesn't diff. between Ford and Mercury in these years. Is there any little 'tricks' to tell the difference?
... or should I just keep the hood shut, and drive the legs off it!!
Thanks in advance.

 

engines with the 59 on the bellhousing are found 42-48 and all ford and merc are 239ci i have run across one or 2 with a 3 1/16 bore which i think are factory replacement engines for earlier models.

 

There were no differences in Ford and Mercury engines from 1946-1948. Drive it and enjoy it.

 

59A block was late 1945 through 1948. There was no difference between Ford & Mercury in that time frame. Th 1942 through the end of war was a 29A block and is a little different than the 59A but is a desireable block.

Drive the dickens out of it!