AZ261 MD80 aircraft had a single screw jack, the B767 has dual jacks which are independent, except that they share structure at the fuselage attachment, which was the subject of AD's in the past related to cracking.
Are you positive about the 767 having dual jacks? I'm pretty sure there's only one screwjack ( although there might be concentric load path redundancy in the event of a failure) with dual hydraulic motors/brakes. It's been a few years since I've flown it, though...