Back then, most people had more common sense. Just replace what's broken instead of forking over more for a matched. Appliance were not a cheap purchase back then but they were made in America when people took pride in their work and a living wage was paid out, even a pension.
It doesn't surprise me these are still going 45 years later. Dryers are simple devices, it doesn't take much to keep them going, especially older stuff like this that's simpler and better built. I see posts about dryers being "tired" or "worn out." Pffft, it's a motor, belt, drum, rollers/bearing, maybe glides, and a timer. that's about it. About the only thing that makes an appliance "worn out" or "tired" is its appearance. Everything else is easily replaced.
As far as the washer still going, well, it's a Maytag....from the days when it was in its prime. That should surprise nobody. I don't get the least bit surprised when I see a 1920's Maytag wringer washer still chugging along, either.