Nick wrote:

I want to install a Motorola (NMO) VHF hole mount in my car's trunk
lid. Like most late model vehicles however, it is made entirely of
aluminum. If your familiar with it, you know the mount fitting is
machined of brass. I've done a few of these on traditional sheet steel
trunks without thinking about this before, and never had a problem with
premature failure from galvanic type corrosion.
Besides electrical/RF degradation, I am equally concerned about the
integrity of the vehicle finish in the event of catastrophic corrosion.
I intend to run about 50w to this antenna.
My question is: If my installation is as waterproof as they always
have been, should I be more concerned about this phenomena while
dealing with brass and aluminum than I was with brass and steel?
I have found a lot of talent in this group. Thanx in advance for
your well-considered opinions.

The threaded brass outer ring has (or should have) and O-ring embedded
in the bottom edge to provide weather proofing.

I would not be concerned with this setup. While I cannot recall ever
installing an NMO on an aluminum auto body, I have used an NMO on a
variety of other outside antenna installations with aluminum and have
never experienced an problem.

Andy