If they did it, they're a fking magician or they rooted the seal putting it in.

I've done them, but only by removing the tranfer case. If you tried to do it with the selector shaft still inside the seal you would definately struggle to get the seal out without scratching the surface. The only way the selector shaft comes out is through the front, thus the housing must come off.

Retail job would be 3 hours, 2 gaskets at ~$8ea selector seal and gear oil.