Ducommun Inc. announced that it slashed its...

Ducommun Inc. announced that it slashed its quarterly common stock dividend to 5 cents per share from 20 cents, payable July 31 to shareholders of record July 15 . . . Chatsworth-based Tandon Corp. said it sold its division that makes 8-inch floppy disk drives to Shugart Corp. of Laguna Hills for an undisclosed price . . . Standard & Poor’s said it lowered its rating on InterFirst Corp.’s senior debt to BB from BBB, its subordinated debt to B+ from BBB- and its commercial paper to B from A3 . . . General Motors reported that it will lay off 6,000 workers for a month at two Cadillac plants in Detroit while it retools for 1987 models.