I do not have a model number or part number on my zoneline it has been damaged beyond readable. However i am looking at part number 51HK00163 & 525Q401871 what is the difference

525Q401871 is not coming up in the system so we don't know what the difference is. It is very difficult to confirm if they will work for your model without a valid unit model number. 51HK00163 is ready to ship if you need it however.

Will this knob work on a 30 yr old model #51CVB212301B through the wall AC/Heat unit

We are not able to verify that. Please contact Carrier tech support for further assistance.