my GUESS would be Allis Chalmers or maybe Ford. Alot of WD/WD-45s out there. Then maybe Oliver or Case
High wage contracts did alot of companies in. Hit both Oliver and Studebaker hard in South Bend in the 1950's. Studebaker never recovered.
Management does make a difference. By the 1950's the Oliver kids didn't seem too interested in the company any more & they sold to white. (disappointed the oliver mansion in South Bend doesn't have more company history)
Management either by luck, pushing distribution and marketing, allowing engineering to design a good tractor, keeping costs down ect helped some survive longer. But in the end (IH, AC White) the sales versus costs still did them in. I think if Allied Signal (destroyed most companies they bought) hadn't bought white and they had gone to Cummins a few years sooner they would have lasted longer too. < management