As a Milwaukee Road collector I love it, but it's not tinplate!
If Lionel really wanted to produce a "tinplate" O gauge BiPolar, they should have looked to RichArt's O gauge tinplate BiPolar for inspiration!
Here's a picture of the prototype for RichArt's O gauge BiPolars.
Below is a picture of the production run RichArt tinplate BiPolar after several changes have been made to the design. The easiest to spot is the elimination of one side window and the movement of the door from the center to the right. Another less obvious design change is the movement of the body attachment points from the sides on the prototype to the bottom on the production model. Above, note the 6 brass screw heads along the side of prototype that are not seen on the production model below. There are many other design differences.
Finally, here's picture of Dick in his workshop next to the O gauge RichArt tinplate BiPolar, which he custom painted for me in Milwaukee's UP livery. To go this this engine I own several tinplate RichArt O gauge passenger car "kits", which someday I will get around to assembling and painting in Milwaukee's UP livery to go with this one-off BiPolar. At the time of Dick's passing, he and I were in discussions for him to make some special passenger cars which would be longer in length than any he had previously made. Unfortunately he passed before he could make them. Now the "kits" will have to do.
IMHO, Lionel's O gauge BiPolars in their 2019 catalog are fine for what the are but they are not "tinplate".
Bob Nelson