You can find one in nightmare, but only in the lowest level of Nihlathak's place, WSK and Throne Room and not in cows. The drop chance is less than 1 in 70000 in 1 player games, however. So yes, I might be satisfied with a 3 socket armor.
If your merc lacks strength to wear a CV, you could socket Griswold's armor with 3 pamethysts, for a +50 bonus to strength. It shouldn't be hard to find one at hell Mephisto... who might be worth visiting for some time before Pits, Tunnels or other L85 areas. He's the best supplier of bread and butter items.