I think the sidings referred to were those in the fork between the Queen Street and the Springburn lines.
I was passing them in the 1970s, when they were almost wholly Mk 1 stock, for the Aberdeen, Inverness, West Highland etc services, rakes plus various loose vehicles and parcels vans. There must have been about 15 or 20 open sidings, plus a small maintenance shed. They would be wholly Scottish Region internal stock, unlike over at Polmadie where the WCML stock was. DMUs at this time were kept along the line at Eastfield loco depot.
In the daytime the spare Edinburgh Push-Pull, Mk 2 stock with Class 27 each end, was commonly stabled on the loop track nearest the Queen Street lines ready for rapid deployment if required.