Probably eluding to oil leaks from the oil pump, oil filter area, and/or oil transfer tube from the pan to the oil pump.

Lorena, Texas (South of Waco)

Best Gasket did not change the part number when their 312 seal material was revised from orange to black.  The 3A52 number is a good number for the revised seal.  If ordering the Best Gasket 312 seal from anywhere but Best Gasket, just insure that you are getting the ‘black’ seal as there may still be some ‘orange’ seals sitting on vendors shelves.  I’ve had good results with the revised ‘black’ seal.
 
Another option is the 312 neoprene seal sold by FordCraft located in Plano, TX.  I’ve also used this seal on the 312 engines with great success.  The Ford Craft phone number is 972-423-4636.

Lorena, Texas (South of Waco)

How much is it leaking?

its dripping pretty good, it could be the oil pump I've not yet started looking at it, been working on the brakes.

DGMFORD
1955 F100
1957 Ford Fairlane 500

I just read this thread.  I didn't see anyone reference the following articles referring to y-block rear seals.  Click on the links below for some helpful information.

http://www.eatonbalancing.com/blog/2009/06/28/warped-rear-seal-retainer-on-a-y/

http://www.eatonbalancing.com/blog/2008/09/10/neoprene-rear-seal-installation-for-the-y-and-others/

Hope this helps!  


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