I just realized that I dont think I've ever told y'all about the most irreplaceable engine in my collection.
...Hazel...the black five is incredibly common. Not this one.
Several years ago I found a listing for a Black Five in Ebay. She was extra detailed and cost more than I wanted to pay, but for some reason...I fell in love. I won, flinching at the price...until I got a message from the seller. She was from Britian, and the seller was a former BR Driver...a former steam driver.
This was his model of his old locomotive. She had been modified to reflect the engine he used to drive. He had got a new tooling to replace the model, so he was selling the old one, but had wanted the person who bought her to know her significance.
5138 (by then 45318) had been scrapped in 1967, but over half a century later her driver still kept a model of her, only replacing it when he got a model more accurate to her. I have the physical representation of a driver's love for their engine, and she is irreplaceable.