Or "how to turn a beautiful new engine into an old, ugly monstrosity".
Modeling the CNJ (more accurately, the South Amboy, NJ area, including the CNJ, PRR and RRRR), there's one glaring omission from O scale available motive power. CNJ had 86 (if my counting is correct) big Mikados, from their original USRA fleet, through 4 additional purchases, all of the latter with Wooten fireboxes, and many fitted with Elesco feedwater heaters, creating one big, brutish, beautiful engine.
Now, until Lionel's recent ($1299 msrp) BTO USRA Mikados, big Mikes have been scarce as chicken teeth in O scale. Hines Lines made a fine one starting in 1946, good luck finding one for sale (or affording it). Not having $1299 (and not being particularly interested in a bland USRA model) or a wayback machine, I decided I'd attempt to build my own.
Now, where to start? A PRR L1s is close, at least as far as boiler size goes (rumor is it was the inspiration for the USRA heavy mikado), and they exist in O scale. Only problem, most have cast bodies, and removing a belpaire firebox from a casting sounded like a *****. 3rd rail made one in brass, but if I wanted to drop that type of cash, I'd buy the Lionel USRA and modify it. Plus, the front of the engine was entirely different.
Since the USRA light and heavy Mikes running gear is nearly identical (other than 1" bigger cylinders on the heavy, and nobody's going to notice 1/48th of an inch difference on the model), and Williams brass light Mikes are plentiful, I figured that would be my base, and I'd modify the boiler and add the trimmings to flesh it out. Now, as luck would have it, the cheapest donor unit I could find was a brand spankin' new, in the box Williams Southern RR light Mikado. BEAUTIFUL engine. Were I a fan of the Southern RR, it would have lovingly graced my collection. But no, the route of the Jersey Devil was in my blood, so a sacrifice it must become!
It took quite a while to get up the courage to disassemble it. Some of the trim came off grudgingly with a soldering iron, but in the end, it had to go under the torch to remove the big stuff. And hey, the boiler came apart in 2 pieces! That surprised the heck out of me (never having attempted anything like this before).