Loud knocking when truck starts
Sounds like you need to adjust your valves. Like was said check your oil pressure to see if it is normal. Adjust the valves with the engine running. Loosen 1 rocker at a time until you hear it ticking. Tighten it until the ticking goes away. At this point turn the nut 1/2 turn more. Move on to the next valve until their all done. What type of oil are you using? Do you add ZDDP to your oil change every time? If you do not you are wearing the lobes off the camshaft.