I'm about the same age as the engine. I don't look that good!...but then I've been 'played with', apparently, a lot harder than this specimen!
(What's the saying re baldies?...'Grass doesn't grow where the action is'??
)
Not ZP of the era, IMHO. Probably paint and/or part cleanliness before painting issue.
Here's what ZP did in the mid-30's...
From Dad's 1835...the engine of which had a steam cylinder casting that completely crumbled...needed replacement. The drivers and trailing truck wheel flanges crumbled badly, needing replacement.
The tender, according to my memory of discussion with Dad, was in this condition within the first year he received it as part of the 366W set (about 1934). Lionel replaced the tender with a brand new one which, to this day, is yet in perfect condition, no ZP apparent anywhere.
Nice looking 726. If you're not the buyer, I'm sure someone will be...soon!
Just sayin'...
KD
