IIRC (and it's been nearly 25 years since I worked at Everett) Mach Trim is a sub-function of the AP on the 767 like it is on a lot of other aircraft. 757s have a seperate Elevator & Pitch Trim (it's the only 757-only EICAS Caution I beleive like the Aileron Lockout Failure Caution is the only 767-only one - otherwise the EICAS list is identical). I remember going on to the first GE-powered '67 with one of the EICAS design team and seeing the Elevator Pitch Trim message - that's how I know the difference. Back to the drawing board as it wasn't on the PW version. BTW the '67/'57 EICAS Lead Engineer, "Ed" Farhner, just retired from BFTC today - only about the third time
- we're betting he'll get bored again....