You wont find a chassis as simple as this one, Nothing to it. But, The body is one of thee most detailed & realistic ones you will see. Unfortunately it was so delicate parts just dropped off all the time when running, As the complete shell is taken from the static model kit.
I've run one of these a few years ago around a track & it was bliss! You wouldn't believe the fun you can get out of the first radio controlled Tamiya.
Parts are impossible to find new & NIB kits are way up there price wise.
If you do run one, Use the original 360 motor. 540 motors are no good in these old on-roaders unless you have the reactions of a Jedi!