Sort of. It is the Chrysler TV-8 prototype developed in the 1950s. The initial prototype was supposed to be powered by a conventional Chrysler V8 gas engine. Later designs were proposed with a jet-turbine engine and a nuclear reactor power plant. It never went past the wooden mockup stage.
Chrysler TV-8 - Tank Encyclopedia (tanks-encyclopedia.com)
One of the issues with using a fission “pile” is that it pretty much only can generate heat.
If in some quantity, enough to need cooling off just while “running.”
The trick is in converting that heat energy into mechanical energy. Converting water to steam is pretty typical, if as much for having had a couple of centuries to perfect steam mechanical plants.
But, that’s not exactly an elegant answer for powering tanks. Whic his why the notion never really caught on.
would not like to be around if it got destroyed