I have a copy of the Scottish Region timetable for 1967 which shows a service leaving Edinburgh Waverley at 1733 with 3 sets that split at Dunfermline Lower, 1808 to Perth, 1812 to Dunfermline Upper (it would have been quicker walking) and 1816 to Thornton Junction. I can recall being in a car passing Rosyth Halt and spotting this as an unusually long set. I can’t confirm absolutely, but it was very likely made up of Met-Cam 101s.