The 767 is essentially the same as the 757. The newer aircraft from the factory are equiped with 3 IRS 2 GPS for updates & VOR DME same as the 757. The older aircraft had only the 3 IRS units and VOR DME updating.
The L1011s that ATA flies either have dual GPS or triple INS. There are no VORs in the middle of the ocean, but the INS units use VOR signals when available to update their position. I was fortunate that the VLF Omega units were replaced with GPS before I got on the airplane.
The 737's we use has two dual IRS's , laser gyro's, updated by dual GPS, VOR/DME. They can go 2.0 hours without anyupdating with zero drift, they can go 6.0 and remain within the required RNP without any updating. Pretty amazing stuff.
The 727 has two Universal GPS unity which seem to do a pretty good job.
On the B-707 I used to fly when I as stationed in Germany, we used two INS's (Inertial Navigation Systems) with a handheld GPS backup for the tie-breaker vote. I think the rules are a little more strict now, but we never got lost.
Now, we have two GINS (GPS-aided Inertial Navigation Systems) and a navigator. Regardless, I always take my handheld Garmin GPS as a last resort. Take care.