Take it to a good mechanic to have a pre-purchase inspection done. It will cost you maybe 1 hour's labour, but you won't have any surprises down the road. The mechanic will be glad to give you their opinion of the condition of the car.
Dakota specs - 6x114.3 bolt pattern, 71.5mm hub bore, +32 offset
Frontier specs - 6x114.3 bolt pattern, 66.1mm hub bore, +30 offset
Aside from requiring hub spacer rings, 71.5 od, 66.1 id, will the Dakota wheels fit on the Frontier/Xterra? I don't know if the lug nut seats are the same -...