Just make DAMN SURE the AWD is working before parting with any money. Ideally get it checked by a stealer or indie, and ask them to specifically check for this.
Give us a link, there's a few too many to suss out which one you're looking at
This one?
http://www.ebay.co.uk/itm/Volvo-V70-...ht_1059wt_1396