Officers believe the drivers of a Pantech-style truck and a small blue vehicle, which were both travelling north on the highway at the time, may have vital information about the November 6 crash.

A 73-year-old woman died in Wollongong Hospital after the campervan she was a passenger in collided with a Holden Commodore towing a box trailer.

The fatal collision, which occurred about 8.50am, was the third on the highway this month.

A 76-year-old woman was killed when her car collided with a truck at Conjola last week, while the week before a motorcyclist died after he was knocked off his bike by a kangaroo and slid into the path of a 4WD at Nowra.

Southern Region Crash Investigation Unit appealed for the two witnesses to the Gerringong crash, or anyone with information about the accident, to contact them on (02) 4256 4694 or Crime Stoppers on 1800 333 000.