A lot of it depends on what the things did. If they were out on the farm, they probably never saw many miles. Around here most farmers only came to town on Saturdays with a pickup. Most women the generation of my mother, who was born in 1906, considered it unladylike for women to ride in a pickup. On Sundays the family car went to church.
Pickups that were used commercially got a lot more miles. We put about 50k miles a year on dirt roads delivering gas and oil to farmers. I wound up with one of these pickups, a 1950 GMC, in 1957 when the block cracked and my father considered it to be too worn out to put a new short block in it. We routinely replaced the 228 short blocks with 248 short blocks. Very few commercial pickups survived. Most pickups that survived were farm pickups and very few have over 100k miles.
This is a picture of a pickup after over 30 years of hard service.
https://www.flickr.com/photos/crenwelgeoil/2825842005/You can almost tell by looking at it that the speedo rolled over several times until it quit completely. It finally got so bad not long after this picture that I made a trailer out of the box.
