Date-coded NEW plug wires and bulk heater hoses can be found via the "restoration parts for Mopars" industry. Usually B- and E-body items, some of which CAN also be used on C-body cars. They have been around for quite some time to fuel the very $$$$$$$ over-the-top B-body restorations of the last 20 years or so. E-body restorations, too.
Seeing to chase OEM production date-coded parts can be problematic, in the long run. Remember, you know pretty much how long they have been awaiting a car to be installed onto, so in their quiet eating, in their containers, the oils in their rubber parts have been slowly evaporating, which can mean the plug wires will not completely unwind from their circular state unless they are heated a bit. Then, their ultimate durability will be less than a new set. For example. Which makes the new-production wires with the correct/desired date coding stamped on them to be the best option in that desire. No different with "never on the ground/mounted OEM-production tires. Hidden dry rot.
As with ANY part on the car, there CAN be a date code somewhere on the part. Which pre-dates the actual vehicle's actual production date. With the production month and year on the production/VIN labels on the driver's door, from about 1969 model year or so.
Back in the middle 1980s, well before anybody in the Mopar hobby getting excited about production dates, I observed some of my Mopar club friends getting excited about these things, related to 426 HEMI engine blocks and such. For those items, it was known (at that time) that a block's casting date could precede the actual build date for the block by up to six months. Just depends upon the actual production schedules of the various items. As
@HWYCRZR mentions.
Just some thoughts and observations,
CBODY67
