Chrysler said today that due to customers' "raised concerns" it would add or replace trailer hitches on some older model Jeeps now at the center of a safety debate between the automaker and the U.S. government.

Mike Palese, a Chrysler spokesman, told ABC News today that the trailer hitch would "provide more ability to absorb some crash forces" in rear-impact accidents.

The National Highway Traffic Safety Administration had been seeking a recall of the Jeep Grand Cherokee, model years 1993 to 2004 and Jeep Liberty, model years 2002 to 2007.

In its initial findings, the NHTSA said that at least 51 people had died in the vehicles involving rear-impact crashes and fires. The problem, according to the government, is the location of the fuel tank.

It is situated behind the rear axle, and slightly below the bumper. That makes it vulnerable to rupture when the vehicle is hit from behind.

Chrysler's action covers fewer model years of the Grand Cherokee, only those from 1993 to 1998, leaving out some vehicles covered by the government's initial recall request. Chrysler told ABC News that owners of those vehicles do not need fixes, unless they have an after-market trailer hitch on the car. Then they should come to the dealer for an inspection and possible replacement of the hitch.

The company still insists that the government's analysis is incomplete and the vehicles are safe and have no defect. The automaker called today's move a "voluntary campaign," not a recall.

Clarence Ditlow, executive director of the Center for Auto Safety, said his group was "skeptical."

"It is a safety recall," he said. "We're no longer arguing over whether there is a recall but what the remedy is. [The] NHTSA has the ability to approve the remedy. What NHTSA needs to do is test the remedy."

Ditlow said his group also wanted Chrysler to expand the recall to include Jeep Cherokees, model years 1993 to 2001. Those vehicles have the gas tank in the same location as the ones subject to the automaker's voluntary campaign. The NHTSA had been investigating that model but had not asked Chrysler to recall it.

Ditlow's group had wanted a shield over the fuel tank as well as a new check valve system to shut off the flow of gasoline if the filler hose is yanked out of the tank in a crash.

Chrysler said it would not be adding shields over the fuel tank or changing the fuel nozzle.

In a statement today, the NHTSA said it was pleased with the actions taken by Chrysler.

"Consumers impacted by the safety recall and customer satisfaction campaign should have their vehicles serviced promptly. … We will continue our investigation into this issue," the group said.

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