Lexa399 - what oil/filter are you running in that truck right now?
There are some filters that make these engines tick horribly.
Can you tell where the ticking is loudest at? I.e. with hood open, closed, wheel well, etc
These engines are known for being mild tickers - nature of the 3.2L; however, it can be worse IF the previous owner neglected to do frequent oil/filter changes. These trucks LOVE clean oil, and really needs to be changed every 3K.
You *may* be able to lighten the tick with very short and frequent oil/filter changes for a few rounds to help clean out extra gunk. Change the oil while it's warm and do not use any kind of engine flush.
Also do NOT use a Fram oil filter of any kind, seems to make them tick worse.
I'd choose to use either Havoline, Valvoline Maxlife, or Chevron regular oil in the 10w-30 viscosity with either a Bosch, OEM Isuzu, Motorcraft, or Puralator Premium plus oil filter.
With no history, it's hard to say whether or not the timing belt tensioner is coming do, but when they start to go, I can tell you they sound like a rod knocking - it's a HORRIBLE and loud sound that just makes you cringe. They typically last over 100k miles, but the 12yrs of age is pushing the max on that timing belt if it's the original.