Go to an army surplus store and pick up a thin sheet of rubber, a piece of sheet metal.
Use tin snips to trim the sheet metal into a shape that you need. Make two identical pieces
Take some black silicone and apply a bead around the inside edge of the metal rings (you are going to make a sandwich)
Stick the rubber inbetween and then use some clamps to hold together until the silicone sets up real good.
Next, use a drill press.. (or drill and a table) and make 8 holes. [4 to secure to the body & 4 to secure the sandwich together]
Get some nuts and bolts to hold the two halves together permenently and then secure to the trans tunnel...