You gave me a shiver mentioning that old non-synchro tranny. I drove school bus in my school years and the boss wanted me to handle a 1958 International. Five speed tranny with no synchro gears. Spur gears all the way and to keep it going you had to double clutch all the way up and all the way back down. The back of my shirt was wet by the time I got back to the yard every day. The boss loved me since I was the only one who could drive it with out grinding.
You had to be strong to drive those old things. I was all of 110 pounds and it kept me in shape. Before I got it, it was a forestry game wardens truck. You knew you were driving, unlike the new vehicles now.