Can anyone provide a part number for a 65 Valiant gas cap?

I need a new gas cap for my 65 Valiant. I don't think there is a new aftermarket one available that actually fits the car. I've seen a lot of Valiant with the old aftermarket Stant S curve chrome caps. But I notice there are several of those old part numbers that look identical depending on measurements. They are also ridiculously expensive if you can find one. Most of the time $80-$100 sometimes you might find one for $40-$50. Is there a cap anyone makes that will fit no matter what it looks like? Mine is so loose I'm sure water is getting in. I tried one for a 67+ A-body hoping it would fit but it wouldn't.