There have been a few variations & changes over the decades.
The earliest Contenders,, had a push button cross pin safety in the hammer,,, before the flip lever.
The earliest Contenders hinge point was in the front,, while the later ones (and easier to open) pivot in the rear of the trigger guard area.
Early Contenders had a screwdriver operated half moon pin on the face of the hammer to switch from rimfire and centerfire.
And the early extractors have also been changed. Solid piece & split type.
The changes happened over time,, as the design issues were improved upon.