My brother bought a new Cortina GT in 1965 - the later Mark 1 with the wider grille and Aeroflow ventilation. My other brother and I decided to give him a pair of what we called in those days, track rods for Christmas. Looking under the car, we found that it already came with what the brochure calls 'radius arms'. Should have given him a fire extinguisher as it caught fire on his honeymoon... The earlier Mark 1 shared its suspension set up with the rest of the basic Cortinas, so that must have been a new modification along the line. You could get optional disc brakes on a British HA Vauxhall Viva (at an extra modest cost), but they were never offered here on our Vivas at all as that would show up the bigger Holdens....