My friend John Bizal, owner of Midwest Military, sells lots of Nos, used, AND reproduction Jeep and ww2 dodge parts. He tells me it goes like this....
He sends a sample or a blueprint over to a few different Mfrs, they send a few samples back. After price haggling, the best part for resale gets the job. Next, you will get really nice quality parts for a while...maybe years even...Then the greedy china man shops around to find someone who will make it cheaper. Then one day the batch of 2k parts you bought, that used to be good, maybe for years, arrives and you put in inventory. So, you still have old inventory to sell, maybe many months later that stock is used up, you open the now 6 month old new stock, it trickles out the door little by little and its a year later you start getting complaints about bad parts