MTH did a run of WP in their UP Heritage series several years ago... in the green/orange/grey paint scheme. But they only produced the "add-on" cars, such as two extra coaches, one full vista dome (now nearly impossible to find in stores), and the sleeper/diner 2-pack. It's the only UP Heritage roadname that they have NOT yet produced a 5-car set with an observation. Not sure if they ever will, but you just never know. I always look in the premier passenger car section of their new catalogs just in case.
David