Read up on the 4th Gen Rams on the different diesel forums. Problems are always exaggerated it seems and I haven't seen much report of issues especially with electronics. Emissions maybe but that already has a healthy warranty I think. Plus you can delete the truck for a little over a grand still if emissions are out of warranty and your dpf craps the bed.
I'd pocket the $2400 personally but then again my 07 had no warranty about 100 mi after Driving of the new car lot due to mods. Only 2 issues I had before 100k mi were steering box shuttle valve locked up. New box and install was about $450 iirc and it was a fluke not a known problem. And the hydroboost pump but those are upgraded and better on the 6.7s and again not terribly expensive.
Pretty much everything I own or have owned has had no warranty and the $ saved over the years on deprecation hits and warranty purchase could prolly buy a new Ram diesel outright.
That said the electronics could get expensive but they're pretty reliable. Know several peoe with 4 th gens with a lot of miles and no issues.