Mannel offers up the part numbers for the caps (see pic).
Ford didn't offer them separate from the engine since they are part of the engine assembly. You buy the whole block. Just because they unbolt doesn't necessarily mean they are a separate part you can buy, so the MPC will not list them.
However they do have a cast number internal to Ford for foundry/casting use and as identifiers for engine assembly.
The thick mains are an easy item to spot as different. The rear cap is different but it's hard to spot quickly so I assume that's why the numbers are so prominent.
