My understanding is that if you want to fly for SWA, your application goes to the "other pile" if you don't have a 737 type. You can get hired, and their policy is that you have six months to get it, but that's only if they hire everyone with their type already. I've also heard that it can be a negative to the other airlines to have a 737 type. They'll know that your first choice was SWA and you might leave as soon as they call. I'm still an outsider looking in, but that what my research shows.