noisy rattle

possiblly timing tensioners

Nick. There are front and rear tensioner on my son's 2003 V6 Same goes for the 99 V6?

if its a sohc v6 there is a front and rear chain. and if it is the rear chain the motor will need to be pulled in order to make the change

Me thinks this is gonna cost me,

this is basically a worst case. it could be something other than the timing chains, but its not uncommon for a soch v6 to have worn tensioners or guides

My 03 began making the same noise at 78000, sounded like what most call a stuck lifter. Pulled the engine and checked the tensioners and the guides looked good. Changed them anyway. A slight improvement (lack of clatter) but not much. A month later I clattered myself over to a friends mechanic to have him look at it. When I started it up again in the bay the engine blew at idle. A golf ball size hole right through the block above the starter. Obviously something with the crank. I found out tensioner problems and blown engines are not uncommon with the engine design. Since I purchased the vehicle new, was a stickler for maintanence, and didn't dog the engine, it didn't blow from abuse.