[Arran]

Dan;
  It seems to depend on the code number, and production run, as to what pilot lamp the Hippo models use, some use a G.E #47 or equivalent, others use a 120 V night light type bulb. I think that the sets that used a 35Z3 (Loctal) used the 120 Volt night light bulb, basically a Christmas light bulb, since the 35Z3s don't have a pilot light tap on the filament. In any event they sell LED substitutes for night light bulbs in Walmart and some other stores, that would eliminate the potential melting plastic issue these sometimes get.
Regards
Arran