This question has come up before, but worth a re-visit. Why apply a preservative?
As Marshall mentioned above, in this bodystyle application the wood is not structural however in many styles it is. So what are we gaining by installing/applying a sealer? Any place a fastener (i.e.: tack or screw) is introduced to the wood, you have punctured the sealer, and with two dissimilar materials, this is where the deterioration will begin should any moisture be present. Even when you inspect original unpreserved wood that has deteriorated, it is always in an area where there was a tack or a screw.
Also factoring in, how many restored cars will ever see, or be subjected to the climate of what the cars were originally. In all likelihood, because the wood flexes with the body as it is being driven, the replacement wood will probably never be compromised by moisture, but more likely will find itself coming apart due to glue degrading over time and/or fasteners no longer holding tightly due to vibrations. Nothing a sealer can do to prolong this IMHO.
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