Diesel or not, learn to fix it yourself or be stranded somewhere far, far, away!
The GM 6.5 diesel turbo or NA have gotten a bad rap because of mis/dis-information generated mostly from lack of knowledge. However, if you take the time to understand the 6.5 diesel or any other diesel you'll find it's not hard at all.
Then learn about GM's injection system design flaws like the pump mounted driver (PMD) being mounted on the injection pump and overheating, then having a mechanic wanting to change out the injection pump to correct an overheating PMD. Remote mounted PMD on cooling plate outside engine compartment solves this issue.
Another issue is the lift pump failure mostly because of lack of filter before it install a good raycor and issue gone.
Cracked blocks/heads are usually due to beating on the diesel (cranking boost w/o monitoring results), improper cooling system maintenance, or overheating during a tow.
Anything can break when you beat on it, so care and proper driving skills are a must.
As for understanding diesels they have no ignition distributor instead there is a fuel distributor w/compression igniting the diesel charge, newer injection is EMC controlled. Factory service manuals can be had for a specific brand, even tech training manuals are available making owning and repairing a diesel worthwhile.
IMHO, any overland/expo vehicle owner has the responsibility to know their vehicle top to bottom and how to do most if not all of the repairs themselves when needed. There are no service centers, road service or otherwise of the beaten path.
Ask yourself can I in the field; break a tire down and fix a puncture, replace a u-joint, fix a hole in my oil pan, replace a wheel bearing, weld a snapped axle, replace a broken brake/fuel/cooling line, diagnose electrical or fuel problems, I can go on and on with questions, but w/o the ability to help yourself when leaving the pavement puts you, your friends, family, pets, others and your rig at risk.
This site covers everything possible for a great and safe adventure, however it's on you to know your rig and it's drive-train and deal w/breakdowns and parts failures.
FIX IT YOURSELF or doing your own preventative maintenance (PM) doesn't mean being cheap it means being wise and self sufficient.