D & H PA-4 A-B-A set

At an estate sale this last weekend, I found and purchased the above train set. There was no box with them and no indication on the bottom of the units about who the manufacturer might be but I presume it to be Athearn. Anybody know if I am correct and if so, what kind of runners these are?

Are they HO scale?

Are the shells metal or plastic?

Are the trucks inside or outside bearing? Early Athearn PA’s have metal side frames with bronze bearings in the side frames. Later ones have plastic side frames.

What does the drive look like?

In HO, PA’s have been offered by Athearn, Hobbytown and LifeLike P2K at the lower price range, and numerous brass models.

Nigel;
You forgot one. Con-cor actually fielded an HO model of a PA-1 patterned after their N-scale one. It came out shortly after the Athearn one was released. It actually ran decently but because the pilot was attached to the front truck as in the original N-scale one , it was considered too toy like, and died soon afterward.

I would say Athearn, just because Hobbytown and P2K would not have been silly enough to paint a B unit that the D&H never had!
Uncle Irv painted anything in any scheme, as long as it sold!