Without knowing anything about your parts I can only say that it is most likely that you want zinc plating. Cd plating brings significant environmental and health & safety problems and you're unlikely to find a small operator who does it.

If you want to test your parts, dilute a small amount of hydrochloric acid (sometimes still called muriatic acid) and apply it to a plated surface. If it reacts by bubbling fairly vigorously then it is Zn. Otherwise it is something else, perhaps Cd.

http://www.mmplating.com/

They do a good job for cad at a reasonable price but are in Toronto.

Kinda fun to watch

https://youtube.com/c/GeoffreyCroker