I had my NV converted by Advanced. I suspect it is probably a location preference. I live in New Mexico and have family in Salt Lake City, where Advanced is located. So, I purchased my van from Ken Garff Nissan, which is located a couple of blocks away from Advanced. They were able to slip me into their schedule and i only had to wait a couple of weeks to get my van. It looks great and the vans from Advanced include 4L and still have the full factory warranty so I don't know why Quigley won't do it.