Does a 2004 Ford Expedition have "Rear Trailing Arms"? Dealership says that they need to be replaced, but a 2nd opinion mechanic says my truck doesn't have such a part.

2004 Expedition you have a lower arm, #11 in the depiction below. Ask the dealership to clarify, I bet they just misspoke, and meant lower arm and not trailing arm, it's easy for a tech or salesrep to get hung up on older nomenclature. I'd also take it to the mechanic and not dealership because it's a basic job and no need to pay the dealership's excessive overhead. It could be a DIY job but only for someone with some experience working around suspension components.