The cover in front of the injection pump needs to be removed for three gear to hub bolts. After these are out shut off fuel and remove lines as needed, and throttle and stop linkage also. Check where pump scribe line is now, make a note whether it lines up with line on case. Then remove the three stud nuts that hold pump to case and remove pump. This pump can't be put back on wrong as drive gear has a pin that enters a notch on drive hub. What trouble are you having, I have repaired pumps since 1976. May be able to help, have had a pump even mailed from Canada, California, and several other states.