Tamiya, made single motor "Motorized" models and dual motor "Motorized Remote Control" military model kits. Both are all metal gearbox setups. Not sure how long they made these great kits but am thinking late 60's, and through the 70s, partly through the 80's... As a kid, I never managed to get one of the metal drive kits because they cost much more money and were rare even back then. This year a lot of these kits suddenly showed up on ebay just before Christmas 2019. I managed to get two of these "motorized remote control" kits before prices jumped to the moon

The first kit I will present here is a M60A2. This kit had parts in in from 1970, 1974 So I am assuming it is 1974 vintage Tamiya kit. I never noticed before but the "parts trees" have dates on them. I have posted pictures of this below.
Now the Remote Control on these kits consists of a "wired 2 ch controller" so the model has wires coming out the back to the controller. Hey, that is all we had back then and we were thrilled to have that! Of course these days, I build these models a "Radio Remote Control" So there are now "motorized Radio Remote Control" as I present them here.
Power source 1s 130mah lipo. The stock motors are wires in series.
M60 on the white table run... https://youtu.be/iwq_9JeL0Wg
Bridge video... https://youtu.be/rRs8ZUh1FZo