Engine noise on hard acceleration

Ok here is what is going on. On a hard acceleration uphill, there is
an intermitant rattle noise coming from either the driver side or the
front of my motor. I have a '99 Ram 1500 4x4 with an 5.8L (119k),
extended cab short bed. I am wondering if it is a crankcase sensor or
maybe the timing chain (hasn't been replaced yet)? Does anyone have
any ideas on other things to check on?