Everything in the jobber parts market is a copy of OEM. Why 'counterfeit' is a such a concern for many, I don't know.
I buy some of the cheapest parts. It's rare that I get a disappointing lifespan.
What you are describing as "jobber aftermarket" parts is VERY different then what I am describing as "counterfeit" parts.
Aftermarket parts are designed by wholesale or brand manufacturing companies. While these companies have an interest in obtaining greater market share by making and selling cheaper parts, they still sell more or less reliable parts with more or less accurate fitment so that they can keep return customers who continue to know and buy their brand parts for less.
Usually aftermarket parts are less expensive then OEM because they dont come with the OEM warranty, or with the same quality control, and they ALSO use cheaper resins or metals or wire or whatever, as well as cheaper hired workers… all of which result in a part that likely wont last as long as OEM but still works until it finally breaks or otherwise fails.
Counterfeit parts, on the other hand, are made by disreputable people and companies in order to trick any consumer into thinking they are buying a genuine OEM part for a great deal. What many consumers dont necessarily understand is that if a price seems too good to be true for a genuine brand part, it is highly likely that the part IS an actual counterfeit with the exception being single "wholesale closeout" deals like those that rockauto sometimes offer.
MUCH more importantly, counterfeit parts that are made with inferior materials, or do not work to factory specifications, can eventually result in damage to even more expensive parts …like your engine!!!
There are more then several threads about just this subject on many of the diesel truck forums that I also frequent regarding air, oil and fuel filters that are being sold as genuine Cummins or Fleetguard on Amazon and eBay, and even by some resale distributors who cant tell the difference, and want to make ever more markup.
These fake and counterfeit parts are definitely resulting in no start situations and even some engine damage. NOT for me, thank you.
As always, it is Your Jeep, Your money and YOUR choice, so of course feel free to buy your cheap parts from whomever you want!!!
Just my .02