All I can suggest is go over it top to bottom. Every single spot inside and out. I do some sort of inspection every single time I go near the truck. I miss nothing.
One thing to bear in mind, as with anything mechanical, is preventative maintenance. You seem keen, so get yourself a check list somewhere, online maybe or in a manual, and do over and above the recommended daily and monthly checks etc.
There aren't really any weak points to point you at as such (except the chassis), although these trucks do have the odd bits to look at when a common failure and fault arises. But most of these are out of anyone's hands until a failure actually pops up.
Finally, as with any diesel (and so many people will disagree, this has been discussed many times on the forum), is oil and filter changes. Again, you seem keen, so trust me, if I could choose only one thing to do to a diesel engine in a prospective maintenance programme, it would be oil and filter change. Ignore the recommended interval and change every 4-6k (I do mine every 4k with absolutely supreme oil and Mann filter). I am qualified to tell you that all oils break down and become dirty; I give not one jot about all the hyped up advertising and promises of magic oil - it doesn't exist, simple as. Oil has a few jobs to do in an engine, clean, cool and lubricate. The facts of chemistry and physics mean that for a certain engine oil, cooling, cleaning and lubricating cannot be done efficiently with dirty oil. Manufacturers recommend and promise huge (and ridiculous) oil change intervals, for a few reasons.
What's mileage and history on the truck?
