Found this individual 3/8"-drive 7/16" 12-point deep socket on Amazon for $5.99. It looks
perfect — except delivery is Mar 1-4. I don't want to wait that long. Stymied again. I tell ya, this is sexism and rank misogyny, pure and simple! Why, I oughta...
UPDATE: After giving it some thought, I realized I could leave the flange and nut untorqued and complete the rest of the Solution installation and perhaps install the rear main seal while I'm waiting for the socket to arrive. If the $14 box ends are a bust, I'll order it.