I'm restoring a 1975 450 SL. Wondering if someone could help me out, I'm looking for patch panels for the rear quarter panels. Car is in good shape except for the part of the back quarter panel that the bumper raps around. What do most people do in this case. I need both sides. I can find every other part that I need except them. Also when I took valve cover off and looked at the timing chain, one of the guide rails was broke. Seems like chain is loose. How can I tell if the tensioner is working or if the timing chain is stretched ?