Years ago I built one of the 10 early 40' PS-1 that were built with cushion underframe. It's on my rip track now because the roofwalk has come loose, which is not my focus for this inquiry. I think the underframe I installed was a kluge, made from Walthers cushion underframe extensions.
I see that these cars are listed in the Hawkins PS-1 reference files. What I don't see are any photos online of these cars. I found an older series of cars 80000-80199, which are basically the 1937 modified standard cars with 10-4 IH.
Did the first ten of these cars get renumbered to make room for these experimental cushion underframe cars? Did the 2nd 80000 series last long? Anything else noteworthy about these?