Sounds like a dealer was just finger pointing. I have personally had two NV 2500's a 2012 and 2016....both loaded heavy. I had a helper spring system installed on the 2016 to keep it close to setting level and that still didn't get it....but never had any problems. Our company has gone through roughly 75 2500's .....yes 75.... in the past 8-years. I can easily count the number of times any of them needed service other than normal preventive maintenance and most are loaded heavy all the time. The only items were brake jobs on a maybe 2 or 3 of the 75, one had to be towed into the dealer with only 300 miles on it, because of a loose wiring harness. Several of them have been used to pull 16' box trailers. the 2500 with a V6 leave a little to be desired when pulling a trailer, but they get it done. That's when the V8 is a better bet. Both my 2500 V6's averaged 15.1 mpg throughout their life....12-13 pulling a trailer and 17.3 on the best days only interstate.
We roll them over at 100,000 miles...maybe that is the diff? My last 2500 had 95,000 miles with the original tires still on it and good for another 10K-15K left. These vans are by far the best someone could want....but there are always a bad apple in the bunch. Chances are that was a bad seal from the start or something out of balance....I would guess nothing you could have avoided.
I just picked up my new 3500SL...I am looking forward to the next 4-years of driving. The 3500 sets "loaded" with all my equipment and tools at the same height my 2500 sets empty....measured them side by side yesterday.
Sorry for long response.....
