The instructions are pretty well correct for the era of the model kit. Cab tilt pumps were almost always to the left of the battery box (LH frame rail) mounted to a bracket on the rear spring hanger. Later on they often located it on a stack brace behind the cab when free standing exhaust systems became more the norm. The default position for a luberfiner was under the battery box but they could also be found in other places, behind the cab mostly. Under the battery box they were almost always painted since who sees it so why pay extra, but just chromed caps were somewhat popular in that location. Up to '74 the third air tank in the US (under the cab) was used for Emergency Parking Brake Release. Prior to the early 80's there were typically only two service tanks since most 3-axle trucks didn't have front brakes until then. But things like that were determined by the engineering dept. based on the specs not customer preference.