Short for "Frank N. Steam".
Found an unused Balboa S.P. MK-5 chassis on eBay and bid low figuring to use it for parts if/when mine broke down. Got it, and it sat untouched in a box for two years.
Then about six months ago I found an old Westside S.P. Whaleback tender at a swap meet; exactly the sort that frequently showed up behind MK-5 Mikados. Bought it thinking I could letter it for the Sud Pacifico de Mexico and swap railroads with my MK-5 by simply swapping tenders.
And then just a few weeks ago a virgin (unpainted) Balboa S.P. MK-5 boiler shell showed up on eBay and I got to thinking "Ya know, you already *have* 2/3 of another locomotive just sitting around..." so I went ahead and bid.
Had to cast my own lead boiler weight, but I had the original one to copy so that didn't prove too difficult (the burns have healed nicely), and after a week or two of fitting the boiler shell to the chassis (You thought they were mass-produced, and that parts would automatically interchange? HO-HO! It turns out that "Hand-built" means they were all slightly different!)
Anyway, herewith the results: Sud Pacifico de Mexico Mikado # 853. The heaviest class of steam engine that ever ran on the S.P.de M. And notorious for bending the then 60-pound rail into interesting new shapes.
A serendipitous locomotive.