The NAMC’s “Catalog of all Series Matchbox Models” (second edition), AIM's “1-75 Series Regular Wheels” catalogue (second printing, 1983), Stannard and Houghton do not list any variations not already identified by Nick.
U.K. Matchbox covered the model in volume 7, no. 3 (Aug. '83), p94, with a follow-up published in volume 7, no. 4 (Oct. '83), p125., but did not identify any new variations.