Is the stock type transmission mount strong?

I never used a poly mount back there so I can't speak to that one, but I have never broken that style mount in a heavy B body with slicks and tons of 1/4 mile passes on the strip. Most of the load is actually rotational and is controlled by the two engine mounts. Trans mount is just picking up the slack. I should also note that I use cheap parts store rubber mounts back there too, nothing fancy.