You should be able to add an overflow bottle, yes. I think those trucks came with one from the factory. Try searching “1993 Dodge Dakota coolant reservoir” and see what comes up. You should be able to mount it in the factory location.

Sounds like you have a coolant leak somewhere. You’ll need to determine where the leak is coming from, or risk overheating the engine. Before you drive anywhere, make sure you top off the coolant in both the radiator and the coolant reservoir.

Do you see anything leaking under the car? Evaporated coolant may leave white streaks or a sweet smell in the engine bay. If your coolant is leaking internally, you may see white smoke out of the exhaust. See this article for more info: https://cartreatments.com/white-smoke-from-exhaust/

Don’t open the radiator cap while the engine is hot.

Is the radiator full of coolant?

I am not very familiar with older cooling systems and have never set up a universal overflow tank, so I’m not really able to offer any advice on which tank is best. I would check Nova owners forums to see if there is a common setup that works well for your vehicle, or if any owners have come up with an alternative approach.

The radiator should always be full, and the overflow reservoir should be between the low and full lines. The owner’s manual should tell you whether you should check this hot or cold. If it doesn’t specify, it probably doesn’t matter either way.

Remember not to check the pressurized cooling system while the engine is hot!