When GM built the GMT 400 trucks, they put a lot of time and money into research. Toyota was killing GM back then. You could but a new Tacoma ,and get over 500,000 miles out of that truck. In the 1970s through the 1980s a GM was shot at 100,000 miles. GMT 400s were also the first GM truck built in a wind tunnel. Where before the 400 trucks, the tolerances were passable at maybe 50,000, tolerances and when the 400 trucks were built that changed to maybe 5,000 tolerances. It was close to what Toyota was doing. These are the American made trucks that were built to compete with Toyota. The problem with all of this is, when you build a truck that can last for 20+ years, there is no need for your customers to buy a new one. The 400 trucks are also the perfect blend on tech and usefulness. Not to complex, but complex enough to make a very reliable truck. The last of the first gen small block GM engines. An engine that had a 50 year + run. That's a lot of time to figure out any and all issues presented by that design. It's down fall was fuel millage. The LS engines were designed for better fuel millage. The early GMT 800 trucks were close to as good as the 400 trucks, but the farther you get away from the 1999 time line, the more BS was added to those engines. AFM is a big issue with the LS engines. AFM has killed may a LS engine. GM just got it rite with the GMT 400 line of trucks.