Originally Posted by
hhdl
FB Gold and Platinum will also appear on the upgrade list for F (including international flights where DL has F) and domestic Premium Select/Delta One. These upgrades only become possible at T-24 and prioritized behind all DL elites and Reserve Amex holders (viz. very unlikely to clear).
Unless something has changed recently, so does FB silver. I have had DL upgrade me while their system mistakenly(?) recognised me as "KL Silver" even though I was actually only Ivory (back then) at that time. Of course, one needs to select flights with almost zero DL elites for this.