The word count limit is never absolute, but if you read the tone of the wording in the various guidelines, you can see varying levels of aversion.
PodCastle's guidelines: "We may run longer stories, but it will be a harder sell."
Pseudopod's guidelines: "...we are quite hesitant to produce stories any longer than that. The longer the story is, the more brilliant it needs to be to sustain audience interest."
So, sight unseen, my instinct would be to send it to PodCastle first since they do routinely run longer stories, whereas Pseudopod rarely does, and I don't know if we've ever run one as long as 10,000 words. Maybe "Flat Diane" and that's it.