Kelly became number two to Neil Warnock in summer of 2003 when Kevin Blackwell left for Leeds United. And, the Blades have not been successful since then.
Thumps Up: Stuart McCall is the new Assistant Manager.
The former Republic of Ireland forward will be under new Deepdale boss Billy Davies who was officially appointed today.
"I'm really pleased to be here," said Kelly. "This is a good football club and I am happy to have been given the opportunity to work with Billy this season."
However the Blades have already revealed there number two, and Blades-mad are pleased to learn that it is Stuart McCall. The young Scot will do a great job for United.