Hi Rob
I'm around 1960 (but not fanatical about it).
I buy what I like the look of. I have to build 8 wagons for my NMRA AP, so I'm doing 4 boxcars, 1 open wagon, 1 hopper, one flat car and one obligatory passenger car.
I'm starting with the box cars, so I need the mesh walkways on top, and the ladders. I have already got the brake wheels.
Cheers