Dont know if this is already suggested but why not put Ostketten in for the Ostheer.
Ostketten was introduced in 1944 on the eastern front, extra wide tracks for panzer 3 and 4s (maybe even more different tanks)
My idea was, just an upgrade for the ostheer Panzer III and IV's to upgrade their tanks with ostketten, for increased traverse and/or accaleration.
PLs comment, im dutch dont watch my grammar...