That factory radio is just so freaking cool. Not sure if I have ever seen one of that style since so many got swapped out for aftermarket CD players and such..... Funny what pops out to different people on super well kept vehicles such as Big Brown. The perfect condition switch gear on the HVAC and door cards is also pretty incredible as well.
I have always loved the Vacuum Florescent Displays that GM used in the dash, HVAC, and Radio through the years. GM's were always richer and deeper than other manufacturers during the VFD heyday...... Nobody uses them anymore and now (to me) they seem special. I think the GMT800 was the last to have them and is the main reason I would never put in an aftermarket radio in my 04 Tahoe.
Got a pic of it turned on? Might help it sell tbh since it's fairly unique to still have it.