ORIGINAL: sevoblast
This is the original version King Tiger, no sound or anything, single motor drive as you mentioned, no recoil etc etc. This model originally came out in 1974 or so. Price is a little steep for one of the older ones, radio or not. On the radio, it may well be an original also, hence a little behind the times. Can you post a photo of the tank and radio?
If you want any kind of sound or more current features such as recoil etc, go with a new King Tiger kit. When Tamiya came out with the full function KT, they didn't just slap in DMD/TO systems, they completely redid the tank. Completely different lower hull, albeit using the same wheels and suspension parts, and many modifications to the upper hull and turret, mainly inside for mounting the full function machinery.
My research, in the past, revealed the debut year of the 1/16 RC Tamiya KT to be 1981. I believe that is also the year stamped on my Porsche KT static kit's upper hull (that kit debuted in 1994).
How is the F/O lower hull different other than having twin bushing road wheels instead of single bushings? I thought is was indentical otherwise to the DMD "only" KT kits from the late 1990s.