Paul,
I "restored" a 79 Caddy Brougham that had been converted to a station wagon about 10 years ago, it had a lot of the lightweight trim you are describing. I'm no metallurgist but I assumed it was just an aluminum alloy with a harder surface or just very thin stainless. It was definitely not anodized, that would have peeled or worn through to show a base metal. I polished all the trim myself including some pretty poor junkyard pieces and had no problem with anything
"cutting through". Do not know for sure if it is the same as your Toro, you might want to put this on the OCA forum.
_________________________
Don Rundgren
1963 Buick Riviera, 1928 Pierce Arrow Model 81
AACA, PAS, BCA, ROA
McKinney, Texas