Some of the Ann Arbor's first diesel locomotives were the Alco S1 and S3 models, arriving on the railroad in the early 1940s. The S1s arrived first proving to be popular and capable, so S3s were ordered to help expedite the replacement of steam. Once again, these Alco units as configured for the AA were not available in N Scale, so I had to improvise.

 

Photos shown here are Arnold S2 units that were retrofitted with NorthWest Shortline wheelsets to eliminate the pizza-cutter flanges that came on the original Arnold models. You will note that I also managed to find AAR Type 1 sideframes from an Atlas SW9, and while I was swapping out the wheelsets I also sliced off the old Blunt-style sideframes and grafted on the AAR-1 sideframes, essentially converting the Arnold S2 into an S3, to match the Ann Arbor's S3 #6 and #7. M&LS #1 is also shown here, as it became AA #10 in 1968 after the M&LS was abandoned.

 

I had all of these units converted to DCC with functional cab roof beacons. These models were brush-painted back in 1998-1999 and have seen some wear and tear. And of course, Atlas came out with a DCC/Sound-equipped Alco S1 in 2016-2017, so I now have a couple of undecorated versions ready to go into my much-improved 2018 paint shop!