My 921 replacements were square cards packed w LED's. I looked for about 250 lumens and abt 3000kelvin color temp (warm white). Frond them on eBay for around $1.50 ea. I bought a few extra in case some were bad. The square ones don't seem to be available any more, maybe the round cards are the current thing.
2013 F-350 CC SB 2WD 6.7PS
2013 Eagle Premier 351 RLTS
-SOLD- 2012 X23B
-SOLD- 2003 Ford Expedition 5.4, Bilstein shocks