Your entire truck is not safe to drive at 75 MPH. 65 MPH is seriously pushing it.
I have had a slew of '49-'53 3100s and pushed them well over 75 from time to time. Was it safe? Not at all. I did it to see if I could, then thought about what would happen if I had to make an emergency stop and regained my sanity and slowed down.
I am no role model in regard to this topic but do feel inclined to offer my opinion as to what is or is not safe with these old relics.
