Topic: Tail Light Housing Stripes

[Countrysquire]

I noticed these stripes on one of the housings that I was cleaning up for a member.  I've owned a number of '70 cars over the years, but don't remember noticing this in any of them.  Is this common?

[7Lscjracer]

Looks like an issue with the zinc plating process called rundown streaking.
I'd say just clean the parts with parts cleaning solvent and otherwise leave them as is to preserve this unique aspect of how they were originally made.