Yes Waltersons is still in business, Fitting the Panzer IV was a mistake when the boxes were first released. In order for the base plate to fit 2 notches have to be cut into the plate or the front screw post has to be removed from the Pz IV.
Its the only way they fit. Base plates have not been corrected but when the new production of the bearing, steel gears boxes are finished new base plates will be offered that will fit Pz Iv lowers.