The CB&Q open-platform cars Denny mentions have an interesting history.
Some of the cars seen are actually stretched wood cars (the cars with the
longer wheelbase trucks) that had been steel sheathed in 1926.
As the conversion program got underway an official asked to look at the
costs associated with the project and determined that applying new steel
underframe/platforms and rebuilding worn-out wood bodies to fit was not
economical and ordered the program shut down. The Bettendorf steel
underframes on hand were instead applied to brand new steel bodies and new
trucks.
The open platforms were retained until the all steel cars in the commuter
fleet were upgraded with closed vestibules, remodeled interiors and air
conditioning. This was in conjunction with the arrival of the Budd
stainless steel gallery bilevel cars in 1949-50 which also included building
power cars for train lighting and air conditioning on the heavyweight cars.
The gallery cars had Waukesha propane A/C. The steel sheathed cars went
into work train service and lasted through the 1960s.
Charlie Vlk