An interesting slide on eBay —

https://www.ebay.com/itm/DUPLICATE-SLIDE-Missouri-Pacific-MP-S12-9226-9223-Scene-N-Little-Rock-Sept-1961/124009822824?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1431.l2648

First time I’ve seen this. MU hoses for the Baldwin pneumatic throttle on a couple of S12 switchers from the order 9220-9232 (part of the 9200-9239 series). These 13 engines were delivered 3-4/52, 7 for MP, 3 for SLB&M, 3 for I-GN. The mounting for the air hoses for MU required a different configuration of the end railings than the typical Baldwin.

Were these the first MP diesel switchers to have MU? (The T&P 800s were delivered at almost the same time, but with a different purpose in mind than being able to shove heavier cuts of cars.)

Doing a cursory look at the relatively few EMD switchers from the first-generation orders, most of the photos where you can clearly see the end of the frame show no MU, so they were evidently originally intended as one-for-one replacements for steam switchers. Later, as the 1100s were delivered, they appear to all be equipped with MU, which greatly increased their usefulness.

Ron Merrick