I have known about this site for a while and I have been finding more and more nuggets of radio history on it. There's top 40 , free form and more. Most of the radio air checks are from the Los Angeles area. The site is called Past Daily. "because ignorance of your culture is considered uncool"

Here's a fairly good quality air check of KRLA and KFWB from the fall of 1967. Parts of it remind me of what I have heard of early CKFH which sounded like it was proto free form. The KFWB segment features the great B Mitchell Reed. Try It by The Standells was number one in LA and you will also hear an ad for Toronto's Mandala.

Here's one from KTNQ of Jackson Armstrong from 1979.

Here's some vintage free form KMET from 1971. The opening ad is for Live Peace In Toronto.

There's a lot of radio content on the site and you can use the search function to find more