Just purchased a 2004 LLY with 210k miles. It needs some work, including head gasket replacing. Also may need some fuel system repair. My question is while I'm doing these repairs what upgrades would benefit me? The truck is 100% stock right now, I'm going to use it as a farm truck, pulling livestock 20k lbs over a distance, some pulling up hills etc... I'm not drag racing or sled pulling, but definitely going to make it work.