Panzer IB mostly complete; and a rear comparison shot to show the differences.
You can see how the engine deck and muffler arrangement is all new; and how there is now an additional roadwheel pair -- plus a stiffener has been added to the rear hull.
Now come the variants....[:'(]
Oh yes, they're remarkably devoid of "doodads", like stowage, etc; because I imagine that Stridor, Mobius, etc have developed their own stowage and roadwheel meshes that they can re-use between models; and they probably can do a better job than me of do-dading it up, like pulleys and tow chains...
Poly Count
Panzer IA: 2,436 polys
Panzer IB: 2,488 polys
Of course, most of this is because I didn't "cut" the roadwheels up....I'm sure someone who can handle the tricks of texturing round shapes can get it down to about 1,800 polys each....