NWSL?

Northwest Short Line makes replacement nickel silver wheels you can use in Athearn diesel trucks.  Try their listing for 40" or 42" wheels that might fit (see the bottom of page 8 here  http://www.nwsl.com/uploads/CHAPTER_3_2013.pdf ).  I think Athearn's PA used 42" wheels.

If I'm remembering right, the power trucks on the old PA and PB were never upgraded to the newer design with plastic sideframes, and retained the original cast metal sideframes.  Other Athearn dummy units from this era had plastic trucks with pointed axles, so if this matches the description of yours the 37120-4 from NWSL may be what you need.  If the trucks are metal with recessed bearings, select wheels with blunt axles accordingly.  While you're at it you could get replacements for the wheels on your A unit, as they'll work even better than the originals. 

Another option would be to scrounge PA power trucks from a train show or ebay, and retrofit those to your dummy unit.  Remove the gears and they should roll just about as well as dummy trucks.  Since these would most likely retain the original style Athearn sintered metal wheels, they wouldn't look or work as well as the NWSL wheels.

Great

Rob,

Thanks so much. The information is most helpful as it contains measurements I can use to determine which ones I need. I'll be removing the dummy ones from one truck and check the measurements. I have to fix a piece across the front to support the No. 5 coupler box anyway and this will give me an opportunity to come up with a first class engine. 

Dave C.