Remember working on Sabena flights ex-SIN in the late 80s, these were combis with the cargo ahead of the pax. Aircraft were OO-SLA/B/C/D/E..
I remember something like 4 pallets in the maindeck. It was a bitch for ground handling.... a/c comes in, deplane all pax, remove the bridge, position the hi-lift, unload / load the main deck (after the lower aft is emptied), remove the hilift and re-position the pax bridge. All in about 80 minutes. (steps were positioned at the rear doors).
Repeat all along the route and it was a looong route.. something like SIN/KUL/BKK/BOM/AUH/BRU.
Crews were nice and friendly... quite tolerant of the loaders walking thru their nice clean cabin..
Anil