I'm fairly certain I will get tired of this quickly, but it is fun now!
This is the first Superstreets vehcile I have bashed that was not bashed by starting with a standard Superstreets vehicle. I had gone by a local model store to get a tank for a flat car load and the only 1:48 they had was this Academy M60. Not too detailed as I wanted, but it had two motors already installed for power.
What I did was:
1 Two pegs on the right side (upper in 2nd photo) fit into the slot in the superstreets alongside the right outer rail, and keep it pointed on the road
2 The tank is designed to steer by differential power/speed to the treads. I wired the two motors together so they get the same voltage and tied their axles together so they spin the same rate. The tank thus wants to really go straight
3 The larger center pickup (from a loco) now installed for picking up power from the left outer rail (bottom side in photo) pushes hard enough up that that side has almost no traction: the tread barely touches.
4 The tank thus powers itself from the right tread only with the left just spinning at the same speed, and follows curves due to the pegs.
5) I weighted the body with about half a dollar worth of pennies all on the side above the pegs to keep the pegs planted in the slots.
I was worried it would not run smoothly with just the one pickup on an outer rail but its pretty smooth. It does groan around turns but it does okay on 21" diam.