Even though LM won the design contracts, the production is shared between both companies. Lol, when you mentioned the Blackbird, I thought you were referring to the old one, not the new UAV...
Before the big consolidation, we had too many companies trying to stay afloat. There was Lockheed, Martin-Marietta, Northrop-Grumman, McDonnell-Douglas, General Dynamics, and Boeing. It just wasn't practical.
Anyway, the US doesn't want to get stuck with just one company that builds fighters, so that's why everything ultimately gets shared between LM and Boeing. Boeing is very good at building AC, but their fighter designs just aren't quite there yet,imo. The Boeing version of the JSF looked like a pregnant slug to me, lol. When Boeing acquired McDonnell Douglas, they got the F-18 and F-15 along with the rest. They weren't in the fighter business before that. I tend to trust LM's designs over Boeing, but like I said, Boeing is very good at production, so much of the F-22 and JSF are built by Boeing, even though they are technically LM aircraft.