ML/GL 2007-2008 are both DPF only, NO DEF.

2009 and up is DEF and runflats.

DPF is a nothing burger, I've had zero issues with it, just use 229.31spec oil or greater is the lynchpin, I've seen poorly maintained DPF vehicles where the exhaust was completely coked in carbon/oil residue. If the tailpipes are dry with a very light sooting, DPF is fine,

I sure wouldn't limit my choices because of PDF.

I've not done airsprings, however, they swap out no different than the steal suspension, the entire shock/spring assembly comes out whole, one needs to disconnect the airlines at the top of the tower.

__________________
Mark
========
THE WHITE FLEET
2016 GLE300d 4-MATIC 38K BROWN!
2012 S350 Bluetec==94k WHITE

2007 ML320 CDI==166K WHITE (FOR SALE)

Under new management:
2005 E320 CDI--140K--WHITE
1995 E300-Diesel-133.5K--THE CAR IS BLUE
1986 300SL--97.5K (European) AND WHITE. Back in Europe!
1991 190E 2.3-73K California Perfect.--WHITE
1995 E320-Wagon-159K--WHITE (recently scrapped)
1987 300D Turbo-213K--WHITE
1987 190D 2.5 Turbo-288K--WHITE