Mine is a 13 finished in June 2012. I remember when I did a factory tour while it was being built that someone mentioned the revision to the height of the trailers to accommodate the higher sitting trucks. Mine sits no different on the new truck than it did with my previous 2015 GMC dually and a 2012 GMC single rear wheel prior to that. It's just slightly nose high and I mean just slightly. When we had MorRyde IS installed last year the technician said the ride height was good and didn't recommend changing it.
I'm not sure when trucks started getting higher. On the trailer side, I guess it would depend on the manufacturer but I would think in the last 5 to 7 years maybe. I'm basing that on mine which was 6 years old in June but it is just that, a guess.
