From about 56 into the 90's, but not all will have 19.5"
GM mostly, but wouldn't rule out ford and dodge either.

I know that's pretty general and covers a lot, but I haven't seen any rules or givens on where you absolutely will find them, all you can do is look.

None to stay away from that I know of, so long as they fit your truck.

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
---All pictures---
"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-