1997 Nissan Truck rattling noise when I start the engine

I was having the same problem with my 97 nissan truck. I found out that the timing chain guide and tensioner needs replacing. I had it done about 3 years ago too for the same problem. After I had it fixed it went away. Hoep this helps. I am currently trying to do the timing on mine, that is where i'm stuck. My book says to line up the grey link to the mark on the sprocket. Problem is, my sprocket doesnt have any marks on it.