There are some variations we could do right now...there are so many different versions of the M3 Halftrack... Mortar carriers, rocket rigs, those that carred the 37mm AT Gun, and the 75mm FH gun, the M-15a1 with it's 37mm Flak gun...
Then there's the whole Pz IV series.
For allied tanks, many of the Sherman series were used by nearly all, as well as the Stuarts.
The M5A1 would make a great, speedy light tank, while a much heavier M4A3E2-76 Jumbo Sherman would fill the halfway gap.
Gotta get one of the Panter series at one point though
- Jig