[Piper]

yep! that's the 1!! We have the overflow portion which fits into the ~1" rubber tube but not the cap. As is on the top of the rad right now, there just is the threaded part (affixed to the rad) which has a male thread on it roughly 1 3/4" in diameter. If you want to sell the one you have PM me and let me know what you want for it.

Thanks !

Cameron