I am in process of replacing both trailing arms (they rusted and broke). My question is, are they interchangeable left to right? I plan on getting some aftermarket units made by a company from Ft. Wayne, IN who specialize in making excellent greaseable units. I wanted to ask the knowledgeable folks here their thoughts and input as to what would a better arm look like? I'll forward this info to the owner of PMT who is making the first prototype (I'm the guinea pig)! He also said that we can get group buy discounts as he has done well with that on the Ford Expedition blogs (I bought a set of their lower bars for my wife's 97 expedition and the quality was MUCH better than the Ford upper units I bought before I knew they existed). Thanks in advance for your suggestions and assistance.