I'm looking at a 2015 3500 SRW CC long bed, 4X4, 23,000 miles.
I am not very familiar with 4th gens like I am 1st and 2nd gens
Any common issues to look for?
Do 2015's need deletes done?
What kind of highway MPG should I expect, at lower speeds - 60-65 MPH .
Thanks!

 

No deletes needed, just check the hour meter to see how many hours/idle time. Not a huge deal since the truck has warranty but something to consider. If the price is right I say jump. My 13 is by far the best truck I have had, I see no reason to tune or delete. It does everything I need in stock form.

Mileage is going to differ hand calculated vs the computer and driving conditions, too many variables involved. That said highway mileage on these trucks is pretty good on the trucks. Check Fuelly if you like, just take the 20+ mpg with a grain of salt.

Make sure it doesn’t have the dreaded shake at 60-75 mph speed sustained. Take a decent test drive.