I would probably attract a lynch mob at AK for talking about such a thing. Well, not really...
Anyway, I have seen a handful of automotive cassette decks with a record function, but never an automotive 8-track deck. It's not something I would pursue, in spite of being an 8-track enthusiast, especially at the price the seller wants, but I thought it worth a mention. According to the listing title, it only records in mono, but I don't see anything in the photos indicating that, and the manual appears to be sealed.
http://www.ebay.com/itm/310698520910
Recording isn't something I would want to try to concentrate on while rowing through gears. Of course I met one guy with a 5-speed '84 Tempo who said something like he would have a cigarette going while holding a Tim Horton's coffee cup in his teeth while driving. To each his own. Here it's illegal to talk on a cell phone while driving; I wonder how the cops would handle recording?