Its not too bad for power and reliablity is pretty decent too my brother had one that had 350,000kms on it and was still running stong hope that helps.
Deisil trucks ussually last forever
I work with diesel mechanics and here a lot of shop talk. The diesel's are very strong and reliable, however you need to be aware that the injection pumps and modules usually cause the most trouble and are expensive to replace. There is a good after market module that mounts at the front bumper where it will stay cool and not over heat. 99,000km's is barely broken most I know have 300,000 to 500,000 and still running with no trouble.
Your so right mount the module in the bumper cold air intake and exaust work and the 6.5 isnt too bad of a engine (but still not a cummins lol)
Looking for a Used Sierra 2500 in your area?
CarGurus has 187 nationwide Sierra 2500 listings starting at $4,999.
Get More Money for Your CarBe seen by 20 million shoppers. Create Your Free Listing
Search GMC Sierra 2500 Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
GMC Sierra 2500 Experts