I spent a lot of time when I got my truck looking for a good oil that was readily available. I came back to the Motorcraft 15W-40 Diesel Engine Oil because it was the only one I could find that was rated as meeting International's specifications for an engine oil. Is that really important? Well, when you consider that International is one of only two engine builders that uses the HEUI type injector system (My understanding is CAT invented the concept of the system and used it but International improved things when they started using a similar system in their engines) I tend to think it should be at least a consideration when choosing an oil.
Now this is sort of apples to oranges but my truck is a 6.0 and yours is a 7.3, but since I bought my truck I have had zero issues running on the MC 15W-40 for the last 35,000 miles. Your 7.3 is far less sensitive to oil issues so you can probably afford to try out different brands to see if you like one better than another.
By the way, where are you in Baltimore? I live up near the PA line in Baltimore County.