as for models (1/56 or 28mm) there are two:
one from Copplestone but I could not find it currently in his website
and one from Tobsen miniatures. Both are of 1950-1960 era and so not very suitable for pulp.
Reviresco has Lenin's car in winter service but I think the scale is 1/72 so I do not know if it can go with the 28mm miniatures from Copplestone or Pulp.
Maybe there is some other models from the plastic scale ranges that can be easily converted to some extend.
Sorry, there is an aerosan model (with armoured and unarmoured versions) by Company B, too.