The OEM bushing definitely needs pressed in. You can unbolt the stay from the head and take that and the bushing somewhere to have it done. Or if you are stubborn like me, you can devise a "gizmo" consisting of a threaded rod, some washers, and a couple of 4 in. floor plates for 1/2 inch pipe and make a press that basically "pulls" the bushing into place. I'd try and explain it, but you almost have to see it. Do a search on the Volvo sites and search for trailing arm bushing. There is a similiar "gizmo" described that gives good pictures and gives you an idea of where I went with this. It actually took me longer to figure out the construction of this "gizmo" then to put the bushing in once I got it figured out.