757/767 rating & continuing qual
The training program I went through used both the 757 and 767 sims. For continuity, there was a grouping of three or four 757 sims, then the next grouping would move to the 767.
Ground school centered around the 757, then talked about differences for the 767.
The IOE included both types. When I go to Continuing Qual training, I never know which type they will give me until the training is posted on my schedule. I have had the 757 for training only once in the last 5 years.
On the line, the 767 is the equipment I fly 99% of the time. I see the 757 about once every 6 months, and find it not to be any problem.
For the fleet, I see 4 different varieties of engines. Neither presents a problem, but I prefer the FADEC types.
The company has a section of the VOL I dedicated to differences between the different aircraft. It's a great review summary.