While inspecting my 99 EB Expedition for a trip to florida I noticed the rear trailing arms looked rusty so I went after them with a chipping hammer to remove the loose rust expecting to paint them. Well there is no saving them as they are rusted through. I didn't expect this as it is from Maryland. I ordered 2 new ones not too bad at $75 for both. I removed one and noticed that the new one is longer by a 1/2". I called the parts dept and found they changed the part and made a note to replace both as the new ones are longer. This will change the pinion angle and slightly move the axle back. Are there any tech guys out there that know why this part was changed? Anybody have any ideas?

 

After reading your post, I better check the trailing arms on my 98 Exp., as I am in the rust belt. How many miles do you have on your Exp?

 

103,000 miles.