Chevs of the 40s and/or Steele Rubber used to have far better (than the original) rubber gaskets/seals for between the bullets and the body.
Chevs of the 40s has a new on-line catalog/order-system and a few items are misnumbered/mislisted and it is harder to search than their old catalog. They do not seem to have the bullet-to-cab rubber seal (it may be in their auto section).
Here is a
fiberglas bullet body that is hidden in their on-line catalog (a new item?).
Here is the page that has lenses, bezel and bezel-to bullet/lens cork gasket.
Steele Rubber does not list the Panel-body bullet-to-body seal but have a seal that I think is for the '39 bullet (60-0122-15).
Tim