EE was repalcing area differential in service truck and when he stretched to guide a part into place he strained his neck and upper back. He did not lose any time and did not seek medical treatment. He did not report injury to mine mgt. until 1/3/06. On 5/3/06 He notified mgt he would be off work beginning 5/4/06 with surgery for 2 pinched nerves and one disk replacement.