Screw Caps for 1.5 L Jugs

I have acquired a bunch of Carlo Rossi 1.5 L glass Jugs from the recycling bins near my house and I wanted to outfit them with screw caps to keep my cider clean and carbonated. Unfortunately, the standard 38 mm caps don't fit, even though they seem to be about the right diameter. The threads are different. Do any of you know if there exist different thread angles for 38 mm caps? or anything else I should try? Thanks.