Stainless steel fasteners are fine. You just need to use anti-seize on the threads to prevent galling (not spalling) and being unable to tighten or loosen them. I experienced that when mounting a sonar transmitter on a boat. It locked up just prior to getting tight enough. I wound up snapping it off and getting a new screw and nut. I used anti-seize the second time.

Galvanized steel or zinc plated fasteners don't have that issue, because zinc is a softer metal and acts as a lubricant of sorts.

Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.