I just replaced the rear sway bar bushings and end link bushings on my 1999 Minnie Winnie which is on an E-450 Super Duty chasis. It was a fairly easy job, however, finding the right bushings required a good bit of time. I wanted urathane bushings instead of the rubber ones. Energy Suspensions is noted for this type bushing, but after 2 phone calls and a couple hours online looking for my application, I concluded they do not have this vehicle listed by application. However, I found the right ones under my nose at both Advance Auto Parts and Autozone. All of them were urathane. Here are the part numbers:
Stabilizer bar End Link Bushings
TRW - Rear 18137 (urathane) $9.88 (you need 2 kits)
Stabilizer bar bushing (Urathane)
TRW Rear - HB1629
Autozone - FA7147 (You need 1 kit)
Now I have all the rear bushings replaced with urathane. I'll drive it this weekend to see how much better it is. My old ones were really gone and it only has 25,000 miles. Hope this saves someone some time.