but can't get old one off.

new one i got from Nissan dealer looks similar but may be bit smaller. it has a half-moon shaped hole on the back so I assumed the old must pull off. No dice - have used tools and brute strength - it won't budge. I even tried the the " no slide" kitchen liner shown on you tube.

 

just replace it with aftermarket radio

 

Welcome and a few more details might help to get some replies. Which OEM headunit is in your Z? The standard or Bose unit? More importantly, how was the **** damaged? Is it possible the shaft is bent underneath the **** itself?

 

It's the original bose unit. the **** is just beat up from fingernails (and now pliers marks)

 

Examine the hole on the new **** for clues to how it slides on. If there's a large indentation inside the **** holding it on, you may have to use a dremel tool to cut it off without damaging the shaft.