"None" is correct - 767/PW4000 have hydraulic reversers, 767/CF6-80C2 have pneumatic reversers (it's a long story). Most of Delta's 767-300s are PW4000, but last I checked they did have a handful of CF6 powered -300s (all 767-400ERs are CF6).
Looking at the pictures I don't see anything definitive that would say PW4000 vs. CF6, but I think PW4000 would be a pretty good bet. The give away is the core exhaust (CF6 has an external plug, PW4000 is an internal plug), but I haven't seen a good view from that angle.