I'm a little confused about a 221 cui flathead. It's a 21-stud with the waterpumps in the heads and a 3 bold carburetor mount. On the first view I thought it's a '34, '35 or '36 Flathead. But the casting on the block shows a "78". The Model 78 was build in 1937 with the pumps on the block.

Now I'm a bit confused...

This is the engine:

 

Earlier heads on a '37/early '38 block? What do the front engine mounts look like?

 

all I have:

 

I believe in the last photo I can see water pump block off plates on the front of the block. So it probably is a '37 block with '36 or earlier heads on it.
Mark

 

Mark has it, that is a 37-38 block (or possibly a later over the counter replacement block) with block off plates where the block mount water pumps would bolt on.

If you go to remove the block off plates be aware that the water pumps had a "hidden" bolt in the water inlet. I don't know if the block off plates use that or not, I haven't installed a set myself.

 

Thanks guys for your help!