<ARTICLE> 5
<RESTATED> 
       
                                                                                            
<PERIOD-TYPE>                   3-MOS                   6-MOS                   9-MOS                   12-MOS
<FISCAL-YEAR-END>                          DEC-31-1996             DEC-31-1996             DEC-31-1996             DEC-31-1996
<PERIOD-START>                             JAN-01-1996             JAN-01-1996             JAN-01-1996             JAN-01-1996
<PERIOD-END>                               MAR-31-1996             JUN-30-1996             SEP-30-1996             DEC-31-1996
<CASH>                                          10,746                  34,880                  34,426                  23,485
<SECURITIES>                                         0                       0                       0                       0
<RECEIVABLES>                                   65,378                  64,779                  66,785                  87,998
<ALLOWANCES>                                     1,271                   1,035                   1,028                     949
<INVENTORY>                                     30,214                  29,679                  30,580                  56,047
<CURRENT-ASSETS>                               112,663                 134,839                 138,793                 189,294
<PP&E>                                         344,622                 347,164                 348,902                 436,704
<DEPRECIATION>                                 194,606                 199,700                 205,097                 209,118
<TOTAL-ASSETS>                                 277,307                 294,896                 294,807                 526,312
<CURRENT-LIABILITIES>                           86,087                  94,343                  88,957                 171,368
<BONDS>                                              0                       0                       0                       0
<PREFERRED-MANDATORY>                                0                       0                       0                       0
<PREFERRED>                                          0                       0                       0                       0
<COMMON>                                         2,507                   2,509                   2,513                   2,517
<OTHER-SE>                                     106,958                 114,553                 120,310                 138,585
<TOTAL-LIABILITY-AND-EQUITY>                   277,307                 294,896                 294,807                 526,312
<SALES>                                        134,158                 277,940                 408,219                 534,478
<TOTAL-REVENUES>                               134,158                 277,940                 408,219                 534,478
<CGS>                                          114,381                 233,886                 346,335                 456,618
<TOTAL-COSTS>                                  119,510                 243,534                 361,541                 478,375
<OTHER-EXPENSES>                                     0                       0                       0                       0
<LOSS-PROVISION>                                     0                       0                       0                       0
<INTEREST-EXPENSE>                                 779                   1,439                   2,141                   3,056
<INCOME-PRETAX>                                 14,101                  33,370                  45,360                  54,322
<INCOME-TAX>                                     5,291                  13,746                  18,950                  11,169
<INCOME-CONTINUING>                              8,810                  19,624                  26,410                  43,153
<DISCONTINUED>                                       0                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0                       0
<CHANGES>                                            0                       0                       0                       0
<NET-INCOME>                                     8,810                  19,624                  26,410                  43,153
<EPS-PRIMARY>                                     0.35                    0.78                    1.05                    1.72
<EPS-DILUTED>                                     0.35                    0.77                    1.04                    1.69