Garageguy, Pictures did come through this time!
"CON12" stands for the conveyor number that casting came off of at the plant. The casting date code decodes as; D = April (4th month) 19 = 19th day of April 4 = 1954. That's within 1 month of the engine block casting date. A good probability that they were assembled together at the Flint plant.
The air filter looks just like one given to me by fellow Bolter
George "Wrenchbender Ret." It has a stamped part number on the underside that reads "91A9600-A2". Turns out to be for a 1939-40 Ferd, so not original to your engine.
There were 3 different "air cleaners" offered for your 1954 truck. Standard (Regular Production) is a dry filter assembly while there were 2 different sized optional oil bath air cleaners (see below screenshot). Pictures of these have been posted by other Bolters in the past. I am unable to snag and post them myself right now, but am sure others will offer theirs so you can know what to look for. Hope this answers your questions.
