It's a hard find but it doesn't have to work. Juist reasonably priced.
I found a working period correct 67-72 Chevy AM Radio knobs and rear mounting brackets and non working speaker for $50 3 yrs ago but the am-fm radios they think are made of Gold. Yes go to 67-72chevytrucks.com you can't find a better place/forum to find info and parts you need. Just watch what you say as the head B ! * * h likes to kick people off for No Good reason, ask me how I know.