Alright, I'm just about to order my replacement K-member Isolators and some of you have already recommended going solid for sure. I was going to grab the Aluminum ones from: SolidBushings.com But before I go through with the order I just want to ask has anyone heard of people being unhappy with the solid ones? My father is helping me with the install and he is insisting that Polyurethane would be the better way to go. The car is a 73' Plymouth Satellite.