dorman prouducts sells replacement petcocks. Try an auto parts store

In many cars, the draincock is a separately available, replaceable part - either from the manufacturer or as an aftermarket piece. Did you ever think to, you know, check with the dealership or at any auto parts store???

Hi so it needs a new radiator.

yes

Someone replaced radiator and stripped petcock unit inside radiator. I don't know if you can replace whole unit or how to fix it if not. Petcock won't tighten and keeps leaking. What can I do? Thanks