THE EE WAS ASSISTING THE MECHANIC BY PRYING ON THE STABILIZER BAR OF A CAT 773B HAUL TRUCK. THE STABILIZER BAR HAD COME LOOSE AND WEDGED IN THE REAR END HOUSING. AS HE PRYED, HE FELT A PAIN IN HIS STOMACH. HE DID NOT SEEK MEDICAL ATTENTION UNTIL 12-8-03. HE IS SCHEDULED FOR SURGERY ON 12-23-03.