I have a 2001 Ford ranger supercab that makes rattling noises. It has a 4.0L SOHC. It makes a very fast and loud metallic rattle wich softens anfter about a second or so when I first start it for the day. If I need to start the engine after that later on in the day, it won't make the niose at all or it will be much less pronouced. There is also a fast rattle noise from the engine area that happens right when the automatic transmission shifts from one gear to the next which goes away as soon as the next gear is reached. The noise becomes less pronouced the longer I drive. What could these noises be? Could they be linked?

4.0l's are notorious for valve rattle on cold start-up. There is really nothing you can do to make it go away short of completely replacing the valve train in the top end, and that isn't a permanent fix. It's is an top end oiling issue from the factory. Just don't race your engine on cold start-up until the rattle stops.

The rattle in the transmission sounds to me to be more of a loose dust shield/heat shield around the transmission or exhaust than a mechanical issue.

These engines are known for timing chain issues, to fix, the engine needs to come out. find a qualified repair shop that has done these before and has the tools to do it.