Transfer case/ vibration over 50 mph/ car falsely showing over heating

I was told transfer case is bad. How long can car go without this being replaced? Car shows that car is falsely over heating after I drive on the expressway continuously for maybe 30 min or so. City driving not so much. It resets after turning car off for min or so and cranking it back. Really ran hot recently and radiator went bad. I would need a jump off once car got water and cooled down. I can't go more than 55-60 mpg without car vibrating. It does not vibrate when stopping. Also, there is a clicking sound coming from the driver side as I'm turning to the left.