If, on the other hand, you are asking about a maximum sustainable speed - or a maximum economical cruising speed - the answers will be different.
75 mph will blow that sucker to smithereens fairly promptly, I think.
Top speed is never sustainable, head winds, load changes, grade changes. And that truck was not built to run flat out all the time.
Though I think everyone may not to go that fast they still want to know what their old car, truck, motorcycle, can do.
