NEW YORK (AP) _ NBC's in-house investigation of the GM truck-crash fiasco that brought down the president of the news division blamed bad judgment rather than a conscious effort to deceive viewers.

In issuing the report done by outside lawyers for NBC, the network Monday confirmed the departures of three ''Dateline NBC'' producers. Like NBC News President Michael Gartner before them, they resigned under pressure.

The report said NBC had made ''misjudgments and professional lapses'' in staging a collision designed to show the alleged fire dangers of the ''sidesaddle' gas tanks in older General Motors pickups.

The truck had been rigged - without viewers' knowledge - with tiny rocket engines to ensure it would catch fire if gas leaked.

GM won a prompt on-air retraction and apology in February after slapping NBC with a defamation lawsuit over the footage aired in November.

Top NBC brass on Monday added its own fury to the outside criticism.

''These journalistic and administrative failures are indefensible,'' NBC President Robert C. Wright said in a statement. ''They should not have happened. They should never have been allowed to happen. And they must not happen again at NBC News.''

Gone from ''Dateline NBC'' are: segment producer Robert Read, senior producer David Rummel and executive producer Jeff Diamond. The report said that Michele Gillen, the reporter who narrated the GM story, had raised concerns about the crash demonstration, but ''the only question is to what extent.''

Gillen agreed to reassignment as anchorwoman at WTVJ in Miami, the network said.

The report cleared ''Dateline NBC'' staff of intentionally rigging the crash to mislead viewers.

''Neither Mr. Diamond nor any other 'Dateline' journalist conceived of the idea to use igniters as a means of rigging the test results'' and did not intend to present false information, the report said.

The report did not specify whose idea the igniters were but said the ''Dateline'' producers failed to consider whether their use was consistent with NBC standards. The demonstration was conducted on NBC's behalf by consultant Bruce Enz and his Indianapolis-based company, the Institute for Safety Analysis.

''I continue to stand by the accuracy and integrity of the segment,'' Read said Monday.

In a statement, Diamond insisted he had acted ''appropriately and responsibly at all stages based on what I knew at the time.''

Rummel could not be reached for comment.

NBC announced that Neal Shapiro, a former producer for ABC's ''PrimeTime Live,'' would take over today as executive producer of ''Dateline NBC.''

Gartner resigned March 2 as NBC News' president, saying he hoped his departure would help defuse the controversy. His successor has not been named.