The first incident occurred in Caulfield on Thursday 1 April 1982.

A 21-year-old woman was threatened by a man with a screwdriver before being dragged into a car about 7pm.

She was taken to an unknown location where she was sexually assaulted.

The second incident occurred in Mulgrave on Tuesday 3 May 1983.

An 18-year-old female had been to a milk bar on Police Road when she was approached by a man on Albany Drive about 7.50pm.

The man was armed with a pitch fork and threatened her before dragging her into a nearby van.

She was driven to another location in Mulgrave where she was sexually assaulted before being released on Singleton Drive.

It is believed the man in the distinctive van had also followed another woman prior to the sexual assault in Mulgrave.

The offender was described in 1983 as being 23 to 25-years-old, perceived to be Caucasian in appearance, fair complexion, 175-180cm tall, solid build with dark brown wavy short hair and moustache.

He spoke slowly with an Australian accent and had rough hands.

The distinctive van he was driving has been described as a white transit/Bedford van with a red and yellow stripe curving from the top rear of the van to the front.

It had a rectangular bubble window at the rear passenger side and two doors at the rear of the van with no windows.

There was also green canvas and dirt on the floor of the van.

Investigators believe the same man is responsible for both attacks and are keen to speak to any witnesses or anyone with information.

Detectives have released digital images of the man and the van he was driving in the hope someone may recognise him.

Anyone with information is urged to contact Crime Stoppers on 1800 333 000 or make a confidential report at www.crimestoppersvic.com.au.