I was just looking at shocks yesterday for a 2010 Phaeton. Pretty sure I'm going with Bilstein. According to this review the Koni's are somewhat stiff. http:////www.motorhome.com/tech/diy/...absorber-test/
That review is pretty old, but it compares the Bilstein's to the Koni's. The Koni's are really expensive.
Best price I found was at Shockwarehouse.com. I didn't search a lot because it will be a few months before I buy. I've posted the prices and part numbers for both.
Edit: I just noticed you have a Freightliner chassis. The shocks I posted are for the Powerglide chassis. Sorry.