In 2001, Nascar began a comprehensive TV broadcasting agreement with Fox, NBC and TNT. That part of history is well documented. But the previous era (when each track sold TV rights separately) is less so.
Wikipedia has two articles about the
1980s and
1990s, listing each race's networks and announcers. However they don't mention ratings. This information can be found on old websites like theautochannel.com and autoracing1.com. I'll add that information here.