I haven't read all posts, so I don't know if this has been mentioned, but keep in mind that a Cab/chassis truck will be 'detuned' compared to a pickup bed truck. This is with Ram and might be on Fords also.
This means that a 'cab/chassis' truck will have less horsepower and torque than a pickup bed truck. I'm not sure why they do this, but I found out when I bought my 2016 Ram 3500 cab/chassis.
I have about 170000 miles on it now, and it has been a good truck. We don't use it much anymore, but it is the only truck I have that I feel comfortable pulling our 40' trailer with.
One thing I noticed when I first got it was that it took longer to merge into traffic when getting on the interstate compared to my previous Ram 2500 which had the same engine, but was not 'detuned'