Another am fm thumbwheel question- original radios not repops

[Ghoste]

Is there a good guide somewhere to the various ones?  68 and 69 would be different would they not?  I understand there were two vendors for them, is this true and what if anything was different there?  Would a dealer installed one be different again?  Which ones had black buttons and which chrome? 
There was a topic on Moparts some time ago about this but reading it didn't answer all my questions.

[Charger-Bodie]

The face lettering is basically the difference between 68 and 69 radios as far as I know. Chrome buttons are from a c body radio.  Not saying there can't be any b body radios with chrome but I don't think they were intended to have chrome.