You will see some references to the diesels having emissions control issues early in their introduction. The first ones shipped in mid 2014 as 2014’s and some got lots of attention at their dealers and here. FCA seems to have fixed the issues (mostly software) by March of 2015 or so. The automatically shifted transmission has been trouble free with only a couple of users reporting any issue. All in all, since the updates the diesel has had less issues reported than the gas but remember many more gas vans are sold.
We have determined that all three variations of 1500-3500 are identical except for rear springs and perhaps brake pad composition on the 1500. If you need the extended then it is only offered in the 3500 and as a tall version.