There's been a vacancy every 3 months recently. The company Says how many spots are available in each base fleet and seat. You put a bid for whichever you want and if you are senior enough and a position was made available by the company you are awarded the transfer. Here as an FO you can only bid to a different base not different equipment. Once it's awarded you are supposed to transfer within 60 days, but the company can withold longer if they need people in your current seat they have to give you tdy protections if they do (per diem, hotels).

As far as displacement. If you get displaced you can displace to whereever your seniority holds doesn't matter equipment. Base or seat. So Dera was referring to you'd be able to displace to 175 if you wanted.