Hi Blue Comet. I have more PRR K-Line Alum, than any other Road.
Bought a 18" Broadway Ltd Set (6-22433) NIB with shipper. The "Fleet of Modernism" is my favorite PRR scheme, it's so Art Deco. Then found an 18" Imperial View Pullman (6-22421). For the head end have 15" Fleet of Modernism Cars; Combine, RPO, Baggage. Makes one beautiful train! Still may get another 15" baggage or 2 at some point (if the price is right).
The other PRR cars I have are 15" Alexander Hamilton Obs and Betsy Ross DOME! The last car listed is by far the most un-prototypical thing I own. But as I said in the start of this post I like Shiny Cars! If you have aluminum cars might as well show it off.
Thanks again for your help and the offer for further assistance!