In the early 80s most of the "portions" were mark one or IIa-c mark twos, air braked, and being non coffin ( no Aircon) in the summer timetable ANYTHING could work them. Duffs were booked most likely, but were too busy breaking down on longer services on ECML, Highland line and replacing shove duffs as they were always getting fixed too.
It would not have been booked 26xxx or 27xxx Mac Rattlers because not all were air braked, but given trains like the bathgate car flats fed locos to carstairs, any "x.." dual braked loco could drop:
40s were more common on the Perth motorail and addexes via Cumbernauld / Larbert but I had a couple on the portion too ( 40047 rings a bell and a 15x while my book is hidden)
The most entertaining were pairs of 20s from the bathgate flats who would chop merrily away to the "'bra'
In 84 it went completely mad, with forties released from most "booked" diagrams they had before, and the miners strike releasing everything from 20s, 26s, Monstorously huge 37s and 47-3s, the latter of which created a lot of flapping in july 84 when they regularily went flat for batteries, completely withering duff bashers while we flailed behinds some humungous 37 nb!
There were loads of summer addexes too, and with Roarers breaking down pretty much all the time on the WCML, Carstairs in its weird middle of nowhere location, became a Mecca!
At one point there was probably more bashers than patients at the loony bin any saturday at 11:30!!