Growing up in the 1970s, I've long had a fondness for cabooses, especially the MP short bay window design. In fact, the lack of cabooses on my portion of the IAIS has been the only major regret I've had about my choice of prototypes. It's been so bad that I've often thought about backdating the layout to RI times, or even starting over with a different 1970s prototype, in order to allow caboose ops. Every time I'd see one of Rob Spangler's, Tom Patterson's, or Bob Rivard's updates showing cabooses in operation on their layouts, I'd get thrown right back into the mental fray. I didn't want to scrap everything I've worked for over this one detail, but I didn't want to continue to ignore my beloved cabooses either.
The UP threw me a bone on October 2, 2006, and again on January 15, 2007, when they mistakenly sent the same shoving platform, MP 13021, to the IAIS as part of their interchange cut. It's shown below on IAIS's rip track as it laid over for a couple days while the IAIS tried to figure out what to do with it following its 2006 arrival.
Considering how ugly its graffiti is, maybe the UP kept sending it to the IAIS on purpose! 
In spite of its appearance, though, the seed was planted, and I began thinking about what IAIS's West End cabooses would look like. This Robert Garton photo from Railroad Picture Archive of a similar ex-MP caboose on nearby Nebraska Central further stoked the fire for me, as it's very much like the look I had in mind for an IAIS-repainted caboose.
I avoided the temptation to add proto-freelance cabooses to the IAIS roster for a number of years, but the Rail Yard Models kit of the MP caboose eventually pushed me over the edge. I later sold the unbuilt RYM kit and purchased one of the new Bluford Shops RTR models, but even then, I still hesitated to do anything with it. I was foolishly putting my concerns for what others might think of such decisions ahead of my own enjoyment of the hobby, which was just plain wrong. This hobby - ANY hobby - is about the enjoyment of the participant, and while I've enjoyed HUGE fun from faithfully following my prototype, this was one area where I felt that the right answer was for me to do something strictly to scratch a sentimental itch.
Below are a couple pics of the first Bluford caboose on the layout. It's not officially in service yet, as it still needs IAIS patches and weathering, but it's a fun glimpse of what's to come. I have two more Bluford models on the way, and at least one of them is expected to get a full IAIS repaint. All will eventually become IAIS 9440-9442, for use by the Bluffs yard job for shoves to the UP, as well as in local and grain extra service. Three may very well be overkill, so I may eventually sell one, but as fast as the first run of the Bluford models sold out, I thought I'd better err on the side of caution.
The first arrival, tied down on the Bluffs RIP track in the same spot as the first prototype pic above.
On the Rover at Atlantic.
It should be noted that the IAIS has an operational caboose, 9431, an ex-ATSF example that's spent nearly its whole IAIS life in Chicago-area transfer service. I considered modeling it instead, or perhaps building a few more ex-ATSF cabooses, but I felt that, for IAIS fans, the 9431 is too much of an icon of the Chicago and Rock Island areas to be believable on the West End. Also, with the influence of the UP in Council Bluffs, I felt that the IAIS purchase of ex-UP/MP cars made more sense here. And then there's that little detail that I just like the modern MP cabooses better.
Finally, it should be noted that, like IAIS 9431, these ex-MP cars will be actual cabooses, not shoving platforms. Though their role is largely the same, they'll have no welded doors, plated cupola/bay windows, etc. Also, since I'm adding these strictly for my own enjoyment, I'll gladly remove them from the layout when guest operators visit if they'd prefer to keep things 100% prototypical. I'll likely do so for some solo ops as well.
