Factory 8 track players, because if you're going to make your 60s muscle car look right, you really should have more than just AM radio.

Olds

Ford

68 GTO

71 Firebird

1969 Chevy

and FWIW, getting any 8 track player fixed up is about 400 dollars. So, it's cheaper to toss a broken one and buy a NOS one from Ebay for 200 bucks

https://luxagraf.net/jrnl/2015/10/8-track-gorilla
http://8trackheaven.com/8-track-collecting/
http://www.barrys8trackrepair.com/8TrackPrices.html
https://www.kijiji.ca/b-saskatchewan/8-track-players/k0l9009