Almost everything else was a 1st generation dmu with 3+2 seating (totally unsuitable for any long journeys)
I raised a metaphorical eyebrow when I read this. I travelled on the Manchester Victoria-Llandudno/Bangor trains off and on through the 1970s - first of all on bucket & spade family days out to Colwyn Bay or Llandudno, later via Bangor or Llandudno Junction on route to walking holidays in Snowdonia with a mate. My 'lived experience' was that the trains were mostly Class 40s plus Mk.1 corridor coaches. Certainly, on odd occasions, a Metro-Cammell DMU did roll into my connecting point at Warrington BQ (cue an audible groan), but I had mostly loco-hauled stock - and exclusive use of a compartment in a Mk.1 SK was a great travelling environment for a young family of five on an Awayday.
A quick check of WTTs from the era confirms what
@Bevan Price said - the great majority of non-summer SO trains to/from Man Vic were booked for DMUs, and I must have just got lucky with my high Class 40 strike rate.
Speaking of lengthy DMUs, one destination I recall seeing several times on the front of multiple Met-Camm lash-ups on the Coast line was 'Rock Ferry'. Back at the time it seemed to me an odd sort of a destination for a through train of 6 carriages - but on reflection, Rock Ferry was a perfectly sensible origin/destination, given the population of Birkenhead and northern Wirral, plus easy rail access from there to Liverpool Central. The Rock Ferry through trains seemed to run every weekday during summer, not just on Saturdays; presumably until the late 1960s they had started from Birkenhead Woodside.
. . . one thing I do remember about the trip, was that it rained every single day!
One of my rail trips mentioned above was to the YHA hostel at Pont y Pant, and it rained the whole time I was there too.
We abandoned our planned hill walking escapades and, on my mate's insistence, took the train to Blaenau Ffestiniog for the day. 1970s Blaenau was a very grim place indeed on a cold, rainy day; at one point we dared to enter a 'local shop for local people' looking for sustenance and were greeted with stares and a total shut-down of a previously vigorous conversation amongst the other customers. My preference had been Betws-y-Coed (where we might have found a cosy and welcoming tearoom or two to eke out the day) but my mate said Betws attracted too many tourists & old biddies and he 'wouldn't be seen dead' there. So Blaenau it had to be.