Thanks, OC MP62
I should have been more specific:
We used and they still use today a Plowvan on the rear of Ballast trains, to spread the stone after discharge, either by centre or side discharging ballastwagons. This double-ended plow arrangement was raised or lowered by a handwheel not unlike the screw handbrakes of the old days. The Plowvan was always attached to the rear and in it the Guard of the train rode(until they were done away with). The plow was operated by one of the Track Gang, if the rake of Ballastwagons were attached for discharge by regular train, then the Guard would be in the Van on the rear.
Ballast Regulators and Tampers were separate machines that weren't allowed to occupy the mainline while a Train, work or regular was in that section. If only a couple or so wagons of ballast were attached then a Sleeper was placed ahead of the last axle of the Ballastwagons to spread the stone.
I've never been able to understand why the D&RGW could never work out the utility of a Ballastplow......