Since this has been a topic for a while I thought I would post my version for those that don't have access to a lot of special equipment. I had one good tailgate side insulator and one that was smashed.I removed the metal insert from the smashed one and cleaned it up. Made a plaster of paris mold of the good one. used silicon dielectric grease as a release on the rubber so it could be removed from mold, once mold has set up I drilled through original 3/16 to find center then removed original and drilled 1/2 hole through mold and inserted 1/2 dowel to support metal insert and used a small screw to hold insert to dowel, clamped dowel in vise to hold insert at proper height in mold, inside of mold and dowel get a lite coat of the dielectric grease as release, slowly pour FLEX SEAL LIQUID into mold till full I let it sit one week to fully cure. Both body side insulators were smashed so I cut one out of wood to form mold of it and poured that one today same process. This one turned out well and so far I have a $20 investment. I used FLEX SEAL LIQUID just cause its cheap but I believe windshield urethane would work as well and may set up faster. In pics original is on left FS part on right