Yes, it is a Px48.
The location, about 20 miles from Warsaw, is a 2' railroad museum. Lots of displays and a short operating railroad. This was a short fan trip for us American tourists.
We visited several museums and rode three or four other 2' lines as well as 30" and standard gauge behind steam.
I wound up spending almost a month in Poland in fall 1991 chasing trains and trams. Quite an experience.
Ira