radio shuts down in reverse

Yes it does.

Seems to be a very good safety feature! .. Operator needs to be fully aware of the surroundings without any distractions while backing vehicle .. Owners manual will have re-set information, index is in back of book .. Since reverse gear is only used momentarily, I think I'd leave it just like is!

I never received a manual (asked several times ). I just want it back to where it was.