64 valiant brake adjuster screw?

If the adjusters were rusty, you should replace everything. Get a "hardware kit", which is adjuster, springs, etc. Costs ~$10 per axle at Autozone, at least my 10" drum one did. I got the later kit (~70+), since all that they had, plus I think it is improved anyway (adjuster design). These were hadly specific to Mopar. Look at Mustang drums of the same year and all will look familiar. Standard Bendix drum design. It is recommended to replace all hardware in a "brake job". The cable adjuster in my 69 Dart 9" drum broke years ago and scored the drum. Don't be cheap with brakes.