X0101 EFFECT 33 LIVE 2011-05-17 13:00:00

F-4

0001013605 PRECISION DRILLING Corp 333-173926 0001518024 Precision Drilling Oilfield Services Corp 333-173926-17 0001518141 Precision Oilfield Personnel Services Ltd. 333-173926-16 0001518144 Precision Limited Partnership 333-173926-15 0001517999 Grey Wolf Supply Inc. 333-173926-14 0001518003 Precision Completion & Production Services Ltd. 333-173926-13 0001518005 Precision Directional Services, Inc. 333-173926-12 0001518023 Precision Drilling, Inc. 333-173926-11 0001518146 Grey Wolf International Drilling Corp 333-173926-10 0001518149 Precision Drilling Canada Limited Partnership 333-173926-09 0001518150 Precision Diversified Oilfield Services Corp. 333-173926-08 0001038893 DI ENERGY, INC. 333-173926-07 0001243350 DI/PERFENSA INC. 333-173926-06 0001038891 GREY WOLF INTERNATIONAL, INC. 333-173926-05 0001064400 MURCO DRILLING CORP 333-173926-04 0001243343 Precision Drilling Co LP 333-173926-03 0001243347 Precision Drilling Holdings Co 333-173926-02 0001243345 Precision Drilling LLC 333-173926-01