Those are some fascinating articles that Clif posted links for. Thanks a lot.
Interesting that the first 2-6-6-2 ordered from American Locomotive Company for the B&A was also sent to the Pennsylvania Division for testing. It proved suitable but as the article about the Pennsylvania Division Mallets
described, Central decided that service on the Pennsylvania Div. "demanded higher speeds" than on the B&A. Thus the decision was made to equip the Penn engines with superheaters (First page paragraph four.)
As far as I could discover the B&A Mallets were not equipped with superheaters. The Penn Div. locomotives are a bit heavier, for one thing. Maybe someone knows for sure?
Again, thanks for the links to three fascinating articles.