Just got done rebuilding two 7028212 4bbl q-jets and found that one had alot thicker rods than the other. (Secondaries?, out of the larger opening)The first had a pair that was gold with no numbers or markings (thin), but the second carb had silver ones with "cz" marked on them (thicker). Both carbs are in great shape now after their rebuilds but when I go from a 2bbl to a 4bbl setup Im not sure which to use. Ive got a 68 malibu that has a 307 w/pg trans but will eventually have a 350/350 combo. I rebuilt the two because I planned on using the second for parts but ended up not needing any. thanks for any help..........