Dude.. as previously mentioned it's a regular thing for manufacturers to stop parts support after a while. The vehicle your trying to fix is 2 decades old.. being "this close" to swearing off FoMoCo because they don't want to produce a bolt that was only used for a small handful of years 2 decades ago is foolish.
Well, let's look at this another way. Most people drive 7-12000 miles per year. Most vehicles are designed to run 200-300 thousand miles. 300/12=25years life expectancy (less accidents etc for the unlucky). The cost to drive this truck was maintenance plus about 1000 a year in that case.
When you purchase a vehicle you do NOT KNOW when the last year of that exact configuration will be produced. In fact they sold with this exact engine, but not this configuration and never told a single buyer and never mentioned it in any sales specification! In fact I purchased this truck used, not knowing that the CONFIGURATION of the listed same engine used for over a decade was changed significantly enough to make the model OBSOLETE within one year really!
Now monetize what has changed in the last few years though legislation:
In today's terms: spend 60,000 for a truck. You must now assume that Parts will not be available by law (regardless of anything a dealer told you the law is clear) for your exact model and configuration in 7 years and the vehicle will have zero value regardless of mileage. SO: 60,000/7= $8570/year.
Now look at mileage: 7X12=84000 miles. 60,000/84,000=$71.5 cents per mile VS: almost every vehicle I have owned looked like this;
25000/300000miles =$8.3 cents per mile.over 15 to 20 or more years.
I am going back to Toyota. I can get any part from the dealer or after market on every Toyota I have owned from 1976 on!
BTW if anyone is using a new truck or vehicle for business, verify the 7 year and you can deduct huge amounts because you can prove that you have no way of assuring repair parts.