Budd Pioneer III Info requested

Can anyone recommend reference books or such that describe Budd’s design parameters in the Pioneer III? By the mid 1950’s Budd was trying Hi-levels, Gallery Commuter cars, High speed Budd cars and the “Keystone” tubular train. How much of the Pioneer III went into the concept of AMFLEET?

There’s a brief description of the Pioneer III cars in Al Staufer’s “Pennsy Power II.”
The cars appear to be very similar to what SEPTA is running on its Regional Rail lines in Philadelphia and suburbs. The current cars have been rebuilt a few times and new cars have been added to the fleet, I believe.
According to “Pennsy Power II,” the Pioneer cars were used as test beds for the Metroliners, which look an awful lot like the Amfleet cars as far as the cross section of the carbody.
Hope this helps.
Eric in Doylestown