I'm working on a T-34 model in which the transmission louvers will be very visible beneath the grill. Would this area be more susceptible to rust (like a muffler, for example), or would it wear like the rest of the vehicle?

No reason why it would be more susceptible to rust than the rest of the tank - the air that comes through it is just ejected cooling air, not engine exhaust.

Of course not that many T-34s lasted long enough to exhibit much in the way of rust while in service, so I'd go easy on the rust myself.

Thank you!