(i used to be a huge military equipment otaku, especially in regards to WWII armor and vehicles).
I actually see the Zombie army having a variety of vehicles and takes at their disposal, stretching back to the very first tanks (after all, they are zombie tanks, right?). The perfect zombie tank to me would be the Tiger I but even in MT terms, parachuting that in from adjacent dimensions would be a little difficult. :)
I'd say that the Zombie Rangers probably have a number of Kampfpanzer Leopard 2 main battle tanks, some Tiger 1 tanks (they had to truck these in) and maybe a few russian KV-2 boxturrets:
and for further reading.... Kliment Voroshilov tanks
and yes, this is one way the Zombie Army delivers tanks to this dimensional plane: http://tinyurl.com/2cqq6u