The Cummins is probably going to be a more reliable and longer lasting motor than the PSD, and it will also get better mileage. Both will have more than enough power to pull your trailer without any trouble. The Dodge has a better frontend and transfer case. The Ford lockout hubs are better than the CAD system in the Dodge. 4.10s are too low for a diesel pickup, so the Dodge has an advantage with 3.73s. The dodge 5-speed transmission has a habit of losing fifth gear, because the nut that holds the gear in place becomes loose. This is usually a fairly easy fix, and a pin can be put in place to prevent it from happening again. The Ford has a better body.

I have been looking for a Dodge just like you are looking at. Around here, it is hard to find a Dodge with that setup and mileage.