Others that may have more knowledge (or access to information) than myself..
Based on photos I can find online, the Penn Central passenger fleet was very Pennsylvania-y. It seems the vast majority of NYC Cars that made it to Penn Central were Stainless Steel cars.
I have only found 1 photo of an NYC two tone gray car lettered for Penn Central.
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And it's a coach.
Did the Bridge, Port, or River sleepers make it to Penn Central service?
~Ian