They literally added panels to 40 foot trailers to make them 45 feet long and extend their useful lives. Pretty common practice, similar to how they "stretched" 40 foot boxcars to 50 foot cars.
That CNW gondola is pornographic
I've wanted one of those for years!
Between Micro-trains, ESM and a couple athearn cars I have more 65 foot gondolas then I'm ever going to need!