FYI: Neither of my ZWs has a plate on the back, above the terminals.
Adriatic, I opened up my 1941 Type R to replace the line cord, and found that much of the insulation is dried and hard, but intact. Probably the effect of age on rubber of that vintage has had an effect. Of course, using a 100-watt transformer during the late 40's and early 50s to run 2 locos plus lights and accessories could have had an effect.
Given the type of material used 60-70 years ago for insulation, in 2014 I'd be wary of anything of that vintage, including R, V, Z, ZW, VW, unless I personally opened it and inspected it. Reading the various posts about power supplies, it appears to be that there is a market for a brick with output in the 14-16 volt range, which would be suitable for lighting and accessories.
Someone earlier had posted that he used a Malibu 12 volt transformer for accessories, which I thought was a great idea. The only problem with that is that my girder bridge and a flashing window light in an illuminated building need 15-16 volts to operate correctly. I suppose I could put the lower power requiring accessories on the malibu, and put the higher ones by themselves on an inner circuit of the ZW, if I can get one that works.
