10 X 1.75 rear drums on 7.25 rear vs. 8 3/4

According to my brake source guru, the flared drums were a snowbelt drum that would keep the road slush and snow from sneaking behind the drum and into the brake assembly. He had a ton of the regular drums for 8 3/4 but none of the flared drums, which he says are not available anymore. He has tons of brake stuff for Mopars from the 30's right up through the 70's, and a lot of truck stuff too. I don't know about the snowbelt theory (he called them Canadian drums), but he sure knows Mopar brakes, and for lack of a better explanation, I'm going with it!!! Geof