When I did work for a classic Mustang parts retailer, less than half the parts shipped from inventory. The less commonly-sold parts were ordered from the manufacturer and, more often than not, took a while to show up because the manufacturer wasn’t carrying them in inventory, either. The retailer didn’t want to hold too much inventory and neither did the parts manufacturer. A carburetor was easy. Some pin that attached to the bumper could take a couple months.

One other issue to keep in mind is the whole supply chain picture, one that I discussed in a different blog about home electronics. Yes, there are aftermarket manufacturers, but the whole supply chain would become disrupted if GM or Chrysler went out of business. The car companies would disappear as well as their immediate suppliers; but so would many of the machine and material shops that supply the aftermarket industry. If the supply chain starts failing at lower levels because GM’s and Chrysler’s parts manufacturers go out of business, then reconstintuting some of those supply chains may be prohibitively expensive for the rest. Making parts scarce and more costly.

But keep in mind that perfectly repairable cars are being junked now by insurance companies and their owners because (sometimes) parts are hard to get. I may have exaggerated in the post (one insurance adjustor said this is a problem about 2% of the time — but he also said that it never used to happen).