I just got an email from Koni regarding their FSD shocks for the 2013 E-450:
"We'll have shocks for your chassis in a few months. The first batch of FSD's are scheduled to be produced in October. Please check back with us." They have them for E-450's up to 2007, so presumably the new ones will fit 2007 to present and beyond. Ford must have changed something in the suspension after the 2007 model---maybe that's when they went to 14,500
We had Track & Sway bars, along with Safe-T-Steer installed which certainly improved handling on our 2007 Workhorse W24 chassis. After driving I80 in Calif, we knew we needed different shocks! We had FSD's installed at Redlands RV and the difference in handling & ride was and still is awesome. I would hope that same improvement would be noticeable with FSD's on a E-450.