Oh yeah, a lot bigger. About 5 or so inches longer....the largest WWII tank would be the King Tiger but I guess they discontinued the Mato King Tiger so you'll have to wait for Heng Long to release theirs (when ever that is) or go Tamiya. I think the second largest would be the Panther G at a close tie to the Tiger I. PIII is a baby tank and the PIV is it's bigger brother.

Anyway, there's tons of after market upgrades for these tanks. You can have a look see at Welshdragonmodels.co.uk, Rctankwars.com, Rccommand, RC-Tank-world.com, etc. The Panzer III is one of the three tanksavailablewith an after market metal hull to add morerealismand a vastly improved suspension, the other two would be the Tiger and KV-1. The Tiger I is more of a neccessaty rather than an option if you want trouble free, unless you can make themodificationsrequired on your own.