I have an audiobook. It is ISBN 1561007773, the unabridged version of Stone of Tears by Terry Goodkind. Although there's no wishlist, there are no copies in the database either.

The problem is condition. All 13 cassettes are present and are in good shape. However, the cover (the box that it came in) is not in good shape. Scrapes, dings, small tears. There's even what looks like dried glue. In addition, the internal case (the one that held the cassettes) is missing. If it was a book, I wouldn't post it.

However, it's an audiobook. The guidelines specifically say that for audiobooks, the box isn't required.

So, my question is this. Would it be better to send out the original, but beat up, box or just the cassettes?

I'd send it, along with a note saying the recipient can ditch it if they so chose. 

I would post it and keep the box. If you want you can PM the person who orders the book to let them know ahead of time. I would give them a deadline to respond by say if you don't hear from them by the mail by date you're going to send it anyway.  Normally I don't do PMs about a books condition but this is one of those things where they might incorrectly ding you because they don't know that audio books don't have to have a box as long as all the cds or cassettes are present.(kind of like the people getting dinged for no dust jacket when there was no RC for a jacket).

I would probably snap it up from you but I don't do cassettes anymore. I can only play them in my car and I always have a kid with me. 

In the Posting Guidelines it says this of audiobooks:

• Audiobooks MUST be the original cassettes/CDs, but do NOT have to include the outer "box" that held the set.
• Audiobooks must be playable.

There's nothing wrong with sending a Requester a heads up, but there's also nothing wrong in posting it the way it is.