First, thanks to all the nice members who took some of their time to reply.
To Tommybza: I checked with various US and Canadian breweries, but couldn't find any reference or link about N scale boxcars on their website.
Finding beer related boxcars is a lot easier Europe, Fleischmann ( and specially Marklin ) have tens of boxcars with beer logos.
To DavidB-AU and rekline: thanks for the links to the Atlas products. I know those 40' wood refrigerator cars doesn't fit the era I'm modeling, but that would be a good opportunity for me to purchase a Mikado steam engine
.
To Hoghead: So far I couldn't locate any model railroad store in Canada carrying the Micro-trains Budweiser boxcar. And now after what jasbourre mentions it's not worth to try to import it from the States.
On the other hand I found that the online store " The Credit Valley " in Ontario has the Atlas Narragansett Beer Co boxcar in store so I'll order from them.