This, even if the company can reclaim the box to take the rest of the tools is theft no two ways about it. If Snap on dealers can pull this **** the first thing you do is get the box and the contents to a secure location, it isn't possible to negotiate any options if they can simply swipe it all from you and leave you even worse off.
I wouldn't really see the issue here. Do the dealers go around checking these serial numbers whenever they see a new box pop up? I've considered a used truck box off craigslist and can't imagine a dealer showing up at my door trying to reclaim something. That's their issue to work out with the original purchaser.
Worse case scenario, a 5k dollar unpaid debt on your credit isn't really that worse then a 2-3k unpaid debt and as someone else mentioned above, sometimes the collection companies negotiate better. If you can't work a feasible deal with the company you'll still need the box in the future, don't sell it cheap, just to have slightly less debt you still can't make a payment on. Your credit will be equally screwed either way. Only sell it or turn it in if doing so will let you create a navigable way through the mess.
