I have been driving 55 years and have never changed any manual tranny oil, rear differential, oil brake fluid, or power steering fluid. Never had one fail either. I did buy a 61 Ford wagon that had a blown transmission that I rebuilt so it did b get new oil. Also a lot of those older cars ,if you changed the brakes, the wheel cylinders were prone to start leaking so they got honed and resealed and new brake fluid.
The only time I changed antifreeze was when the radiator needed fixed.
In the 50's I use to rebuild those Chevy 2 speed Power Glides for people for $50.
I'm a compulsive one for making sure the driveline and front ends are greased though
