Looking at trading my mustang for a 99 model GMC 2500HD 4X4 truck. truck is super nice but don't know much about them. Can someone help me a little, like its the 6.0 liter gas engine. Heard they were bout bullet proof but let me know if other wise. Ask about tranmission and rearend said nothing ever happens to them. But truck has 157000 miles and has a 6 inch fabtec lift. Let me know if there is anything bad about those trucks.