There are ( as of June )new requirements for , exporting vehicles from the USA.
You must first export from the USA, before you import into Canada.
You also need to be aware of, the sales agreements in use in many US states that do not have any provision for a cooling off period, once you sign, the deal must go through. Montana has this.
There will be no tax credit for any trade in, and providing the required paperwork ( recall compliance ) on anything you try to trade into the USA, can be problematic. You need to import any trade into the USA , before you can trade it in, doesn't matter that it was built there, it's been out of the country and has to meet import requirements.
A couple of posts on the subject, I'll track them down and link you to them.
Also the Canadian RIV ( Registrar Imported Vehicles) link.