Lionel Standard Gauge Commodore Vanderbilt Tender Zinc Pest

Great pics - thanks for posting - although it's hard to tell from my picture, it looks very much like mine.

Fortunately, all of the paint on mine seems to be firmly intact.  Fingers crossed.

And thanks to @Sean's Train Depot for the earlier insight into the casting problem.

This may not help @macdaddy , but at least you'll know you're not alone.

My standard gauge Lionel CV tender has the same problem, although not to the same extent. Only the die cast back end of the tender shroud is affected See below -

More interesting is that my standard gauge LCT (MTH) Blue Comet 400E tender has the same problem over it's entire body, as shown here -

I've had both of these engines since new, so I know that this is how they were delivered from their manufacturers.  The paintwork on both engines is flawless. Neither tender shows any cracking and both have proven to be structurally sound. I used to attribute the rough finish to faulty paint work. Now I realize something else must be at play here, but what I don't know.

- Mike

Thanks everyone for getting back to me. I feel better knowing that these were put out the door with these issue rather than something that is changing in the casting that will eventually become a major issue.