If ALPA was a union rather than an association of independent MECs sharing common bylaws and a common tool box (ALPA national) your union number would prevail. No preferential interviews, you would just use your seniority number to pick up a contract at an ALPA carrier on equipment you are qualified on when there was an opening. Of course seat pay and work rules would be set nationally. This is how ship drivers do it. Take a six month contract as Captain hauling oil up the east coast with Chevron, take a few months off when it’s done if you want, then go to the union hall and grab your next contract with Shell or whoever. But the old timers opted (and / or were coerced) into not following this model back in the day—read Flying the Line for why—and it’s just a fantasy now.