33w and 415 Mechanical Horse and Open Wagon (1947-59)

Hi, the no. 33w Mechanical Horse and Open Wagon is a familiar item. Pre-war it could be realized by combining the independent nos. 33a and 33c. Post-war it was available for 10 years (1947-1957), indeed, as no. 33w. But there is also a Mechanical Horse and Covered Wagon. Many of you may have seen an example every now and then, but not often. Above two examples, my post-war version on the left and David Cooke's nice pre-war version on the right. Still, it is never mentioned officially as far as I know. So, my questions are: a. What catalogue number or other reference can be attached to this model? b. A regular trade box of the no. 33w Mechanical Horse and Open Wagon will not do for this model (see image above). It will need a higher packing than that. Has anybody ever seen a trade box with/for this covered model? I look forward to any ideas or comments! Kind regards, Jan Werner