Thank you, Toni! Erm.... Both those billboards are also your own non-DLS items? (Never mind, I found those names by other authors)
I do think you can upload your fire station. Here is Mason Taylor's license from the config.txt file (bold emphasis is mine):
"This model is distributed to the community as freeware; please feel free to reskin as you wish. No problems at all with the uploading of reskinned versions for the enjoyment of others so long as they are free and my original work as creator is credited. "
EDIT: Unfortunately Pencil 42 did not put language on his billboards until 1920s 5, and the rest say: Redistribution and use, with or without modification, are expressly permitted. But I guess we can't assume about 1920s 1-4.