At one time, a shade tree mechanic, with a proper set of tools could take apart a car and put it back together again with nothing more then a Motor Auto Repair Manual to guide them and advise them to the clearances and tolerances and the proper procedure to disassemble and reassemble the components.
Today we deal with computers. Body Control Modules, Powertrain control Modules, etc. Within that computer is a program. At one time it was acceptable to have one bad line of code per every 10 lines of code.
As long as the vehicle ran the dealer could reflash the computer when there was an issue and programmers constantly worked to rewrite the code - even after the vehicle was built and sold.
Today, unless you have access to the updated programs and a Tech II to reflash the computer, diagnose the computer and do simple maintenance such as a pulse of the ABS to pump up the brakes - you can't do a proper job of repairing your vehicle and all you end up doing is throwing parts at it with the hopes that the light will go out and the problem will go away.
Some things are not hard to figure out if you have the proper skills and training and the proper tools to work on it.
The transfer case for instance uses the same clutches and steels as a TH 400 - which has been around since the 1960's.
The transmission has similarities to the 700R4 - which was basically a TH 400 with overdrive - just electronic shift and computer controlled.
The engines has both internal and external problems.
Sensors that were never properly designed or installed, materials used in the block, pistons and heads that were marginal at best when new.
Brakes and rear ends and wheel bearings that were never designed for lift kits, larger tires or even the tires that the vehicle came with.
Simple little things like window regulators that fails usually after 60,000 miles and electronic locks on the door handles that sometimes doesn't even make it that long.
Yes there are some things that you can replace yourself and save a couple of dollars, but you also have to know about issues associated with those parts such as problems with the calipers, brake lines, brake pad sliders, pins, and that is just one issue with the brakes.
Once those vehicles gets so many miles on them, they just seem to disintegrate. I can't say much else that is any better about the Fords or the Dodge's.
I manage a fleet of GM vehicles, I deal with these problems on a daily basis.
I have a guy at the GM garage that I trust, that is the only person that I trust with my repairs. If I can't fix it I send it to him.
Usually I just walk in the door, I tell them what the problem is and what it needs to be repaired. They either approve the repair, or they diagnose the problem themselves and then they basically do what I told them to do in the first place.
I worked for a year at a major junkyard.
I disassembled all makes and models of vehicles.
I saw everything that went wrong with those vehicles when they were new and I knew how to take them apart and put them back together again.
All I did was give some advice - how to fix a known problem.
And if I tell you that it is not as simple as just forcing the old part out and forcing the new part in - it is not because I am trying to be mean, but because I have had experience just trying to do it without the proper tools and equipment and have experienced failures or problems because the vehicle was not repaired properly.
If GM would have stopped making new trucks when they came out with the 1979 Silverado, we wouldn't have all these problems we have today.
Probably the best trucks GM ever made were between 1974 and 1979....
The newer trucks were nothing but garbage, too much plastic and not enough steel...