I have owned 2 7.3's, a 6.0, and now a 6.7. Each one was a noticeable step up in towing performance. 7.3 super reliable but no integrated brake controller or exhaust brake, 6.0 lots of mechanical issues but noticeable more pulling power than the 6.0. PSD after 2011 built in controller, (works great) & a built in exhaust brake, quite, and no wait to start - starts like a gasser. I'm told it will wait if it's cold enough, but so far down to 20 I have not seen it. Set cruise and it will keep you at that speed up & down hill towing or not. As much as I liked the 7.3 to own 2 I wouldn't consider going back old school. Millage on all was about 12 towing.