Caprotti 'Black Five' No. 44743 was paired for a time during coal consumption tests in February 1949 with one of the two coal weighing tenders built in 1946. These tenders were intended to help collect data on coal consumption and locomotive performance and had standard frames and running gear. Their 3,750 gallon tanks were fixed to the frames as usual but the 8 ton bunkers were separate entities fitted inside the wells and suspended on shafts running along each side. The weight was transmitted by the levers to steelyards at the rear, which could be used to weigh the contents when the tenders were stationary but were locked to brackets fixed to the frames when in motion.