My dad has a 1970 C/30 the cab is completely rusted out now and it is in the back of our property. But the inline six and transmission work fine.. It was on the road circa 2008 or so. It was originally purchased for working in Galveston Port, so it has seen it's share of salt.
Your father's truck was probably exposed to the salt roads.. They destroy everything in short order.. brutal conditions there.
But ya, the old cars customers brought it did experience repairs and we could keep them going until the inevitable stuff would happen and total them.
What really sticks in my mind is the difficulty in serviceability and the disposable nature of the modern cars. The abusive conditions in which the mechanics are forced to work due to the placement of components.
After such abuse I will gladly adjust points, or even pull and rebuild the drivetrain with a smile on my face knowing that I will be an old man or dead before it needs any major repair again.
Have you ever rebuilt the a/c system on an old and a newer car...night and day! Same system pretty much except the new cars components are placed in ungodly brutal locations!
But I am becoming aware I come from a bygone era of wanting to keep a car. I think most people have cushy office jobs/ or simple tech jobs and the money comes in like water and they spend it on new cars accordingly.
Maybe once I get the chance to go back to college I will join their ranks. Except I'll just buy an old car and be happy.