The title says most of it. We would be assuming a pretty much unlimited R&D budget, and the vehicle to be remote-controlled or automated.
EDIT/CLARIFICATION: Could an RTEG power an APC-sized vehicle if shielding wasn't an issue?
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I'm going to put aside the powerplant issue - as @o.m. already covered it.
For a remote control vehicle, with 1970s technology, it's at the upper-limit of what's possible.
Now, the Radio control part is relatively easy. What is slightly more difficult is getting enough real-time sensor feedback from the APC. Think of Camera quality in the 1970s and how much bandwidth there wasn't. Everything was analogue and very low-res. Not to mention Bulky - this makes the remote control from a safe distance difficult - but not impossible.
In terms of functionality - an APC designed from the ground-up to be remotely operated is feasible for 1970s tech. We do have autoloaders, remote servos etc. The big issue though is reliability.
For Autonomous, however, the answer is absolutely not. There is not the Processing Power, the Storage capacity or even the coding language - I mean Oracle as a Database wasn't released until 1979. Then you need all the digital sensors, Fibre Optic (which okay, was sort of invented in the 70s, but you didn't get multiplexing until I think the 90s).
Even if Money was absolutely no object - you simply lack the computing resources necessary to make an Autonomous APC - either they haven't been invented yet or they are nowhere near small enough.