It's pretty safe to say that the 6000 would have been a lot more popular had it not been for the issues of the original models. It's one thing to have problems in only one area of the machine, like say the transmission. But when they were re-worked at the factory or dealership and went from red to blue, almost everything was gone through and updated!
It surprises me still, to this day, that Ford was so careless with the introduction of the 6000 in 1961, after what happened to the first SOS trans in 1959, and of course the Edsel in 1957. I think management must have had more money than brains back then.