Probably have to re-valve and rebuild them soon which will cost you to do so consider that also.
How much mileage did he say is on those? Plus their the old DR style CO's not the newer Icon ones so they must have some mileage on them.
You can get this new for a few hundred more and it's comes with a warranty and it's specifically valved for the 4th gen.
Full 2.0" suspension kit