Thanks for the info on the 1588TX GM. Good to know that another exists.
I have always been interested in tenders, as the tender can define the set. There are so many interesting variations, in order to mate certain cars with certain locos.
Another odd gunmetal tender that I have is a 260T with diecast top, nickel trim, brass LL plate and latch coupler. I am guessing that it was made for an early gunmetal 260E. It came to me alone.
The finish has wear as you can see, and thick paint chips imply to me that it was dip-painted, as were most pre-1935 trains. It is unusual for gunmetal finish to be applied in a manner other than spraying.