I try and do as much on my vehicle as possible, however IMO, there are some jobs that are better left to a professional, or at least someone who will warranty to the work if something goes wrong.

I had my timing belt and cam shaft seals done at my local Nissan dealership back in Feb of this year, and within about 2 weeks, I started leaking oil.

Long story short, when I finally got into the dealership to get it checked out, they found that it was the camshaft seals that were messed up, and that's where the leak was coming from. The admitted it right away, and fixed it on their dime.

They EASILY could have said it was something else (I suspected that it was the cam seals anyways, but chose not to say anything to them until I heard their verdict) but they manned up and said that they would be fixing the problem under warranty.

I general, the more you know about your truck, the better protected you are when it comes to *extra* work ANY mechanic is suggesting. It's not limited only to dealerships.

THIDX - PM sent. Cheers!