It looks like just a standard wooden pushrod setup, similar to what is actuating the elevator. Make a new one from a piece of 3/8 dowel rod fixed on the ends like the one you have.
I think you'll find though that there will be more to getting this old bird flying again that just hooking the rudder back up. Plastic deteriorates, so you may need all new clevises. The covering may or may not be sound, and you certainly don't want it coming off in flight. The bellcranks for your ailerons (maybe flaps too?) are probably fine, but if they are loose you'll need to bypass them and create individual aileron servo mounts in the wing. And that's all assuming that the glue hasn't generally deteriorated and there isn't old crash damage that hasn't been properly fixed. I restored a couple of old planes like this early in my time in this hobby. It can be a labor of love, but it is never simple.
Also, if you have only flown drones, you don't have the piloting skills for a model warbird. You'll be familiar with working the sticks and flight in general which is good, but you don't yet know how to land, how to recognize a stall and what to do about it, or how to keep orientation of a drab colored object moving at 70 mph in the sky. I don't mean that to say you shouldn't take up traditional model flying, only that it would be wise to get with an instructor and learn some piloting skills while you are working on this plane.

Keep us posted on your progress. It's a guarantee that unforeseen issues will arise, but that's all part of the process. We'll be here to help you.