I would think that there were still Millions of Model T's on the road in 1945.
Back when they knew parts without having to look up things on the computer. Had a friend who started in his dad's garage about 1925. He said back then parts men knew what they were doing. He said lots of things but I believe he was right on that. I won't get into parts changers and old guys who knew how to fix things.
No computers that's certain but really large catalog book stands for the different vendors they bought from...Which as I recall it was this way clear up through 1986, which is not that long ago, really. :P
Warren, I know what you mean. I use to walk in and tell them I needed an 1157 bulb and they would ask, "one or a box?" and then give it to me.
Now I walk in and say I need an 1157 bulb. And get "what year is the vehicle? Engine size? Two or four wheel drive?
And sorry to say....That's when I walk out.
I do a lot of business with an older parts man that works for NAPA Started in the late 70's will retire next year (I'm gonna miss him) last year I walked in with a broken bendix spring from my "T" I was joking when I said do you have one of these? He said yes but they were at the warehouse but he could have it at his store by 2pm it was about the same cost with shipping as the vendors so I bought it, the 12 volt starter has failed in it's mission to break this one! The kid he was training was amazed that he didn't need to go to the computer to look it up.
I worked at a state college where they taught a course in auto parts management. In the class room were tables that were set up with the parts catalogs as pictured above. That was in the mid 80's as I remember. They began using computers a little later in the classrooms and eventually dropped the course. Now everything you will ever need is in the palm of your hand.
The reason why old time parts guys used to know the part numbers without looking them up is because there was not a lot of numbers to know. Today there is such an incredible proliferation of part numbers no one could possibly memorize them. When I started in auto parts in the 1980s a store could have 20 brake pad numbers, 10 spark plug numbers and 20 gasket numbers and be able to cover 85% of people's needs. No such thing today and that's why it's hard for a parts store to stock parts.
Thompson Products became the "T" in T.R.W.
Heck even today a good parts store has a rack of catalogs on the counter.
Same holds true for Sears Hardware. I worked at one nearly 30 years ago while I was in college. They trained us for two weeks before they even let us work in the department.
We knew our tools, knew our department, knew how to count change properly and knew how to courteously speak to a customer. Apart from a few college kids, most of the men in the department were lifetime employees who were working toward retirement.
My how things change.