Hi Shorn, we had quite a discussion about this sometime early last summer I think it was. At that time I was prepping my car for the summer activities and needed a seal as well. my car is not restored and not exactly a cherry situation. So sometimes I'll try anything. As it turned out i bought good quality, 100% silicone chaulk and laid a thick bead of it(good 1/2 inch or more) around the trans tunnel openning, then set the fibre glass tunnel over that and bolted it down, wiped smooth the excess and vola, a terrific seal. I later remembered that one of the reasons I had removed the cover was to replace the u-joints and I had forgotten to do that, so I had to remove the cover a few days later. the silicone chaulk, after sliding a knife edge all around came away perfectly clean and almost in one rope type piece. Upon reinstallation, i rechaulked and it is as tight a seal today (after a full summer of driving) as when I first put it in place. Maybe you can find more in the archives.
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