So my grandfather was an auto mechanic for almost all of his life, and one thing that he had was old manuals from the 30's to 80's. Found a few that this forum may be interested in. Like these three, all of them for vehicles from the 50's and earlier.
The Dykes- $30 to $40 to the right guy- not that rare. Motors Manuals- my experience is $10-$20 if you are lucky.
Ya I didn't think they'd be worth much of anything honestly, but thought it was neat considering it's not something you see a lot of in my travels, where everything in digital. Once, a long time ago, I was looking into starting up a shop where I'd do nothing but old car restos. That's before I realized that I'm not mechanically inclined, and very poor. At least I've got the books just in case I win the lotto.
I rediscovered that blue one in my collection and will be posting some stuff on the Friday art thread. There are some cool line drawings in the ford subsection on how to make your ford faster- from 1919! That was a hundred and a couple of years ago.