I have a 56 F100 donor parts truck that has what seems to be a passenger car y block.  I say this because it has a front sump oil pan.  The valve covers have FORD stamped into them.  Any ideas what y block this could be?

Bottom of the page, “information center”. Various casting numbers, etc.

http://www.ford-y-block.com/

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

http://www.ford-y-block.com/Block%20identification.htm

From that same web site page, there is a note that reads as follows:

• Block identification number is generally on side of block above the oil filter for blocks cast at Cleveland.
• Dearborn block I.D. number is near the distributor above the generator. Most Dearborn blocks were used in trucks. No Dearborn blocks were made after 1957.
  
• There were no special truck blocks.
  
• Heavy duty trucks with forged steel cranks used C1AE or C2AE car blocks.
• Most Dearborn blocks after 1954 were 272's.
  
• Most 292 and 312 blocks are from the Cleveland foundry.
  
• this info is from www.ford-y-block.com

NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

As has been brought up, casting part numbers can shed much information on the year model of the engine.  Casting dates (different from the casting part numbers) can be found on the block, intake manifold, cylinder heads, and timing cover which can help to identify if all these parts came on the same engine from the factory or if you have a hodge podge of parts. The valve covers having FORD on them points to the valve covers being at least being 1960 or newer.

Lorena, Texas (South of Waco)