Pretty sure the AA means aluminum. What's the motor?

 

Trying to figure that out as well. The following code is on it D4DE-6015-BA 605

 

There are 6 timing covers for the SB Fords. Any one will fit on the 289, 302, and 351W, but it depends on what you're attaching to it.
Windsor SBF Timing Covers
The engine I just took out was originally out of an F-250. The timing cover was completely different than the ones shown on the link. Water pump went the other way, and the PS and Alt brakets on it were mounted higher.

 

The timing covers are all aluminum. The ones for an aluminum water pump will be C2OE-D, C3OE-B, and C4OE-A. They are easily identifiable as they will have "channels" between the water passages and the center of the cover, since the water pump has no backplate, where the later cover for the cast iron water pump will have a flange all around the water inlets for the pump to seal. Pictures below. The REAL early covers will have a oil filler spout as well.

REAL early cover.

Early cover (aluminum pump)

Later cover (cast iron pump)