| EMC AA | |
| Powertype: | Diesel-electric |
| Builder: | General Motors Corporation (EMC/GM) |
| Builddate: | August 1940 |
| Totalproduction: | 1 |
| Aarwheels: | A1A-3 |
| Locoweight: | 2473401NaN1 |
| Weightondrivers: | 977001NaN1 |
| Fuelcap: | 1200usgal |
| Primemover: | EMC 12-567 |
| Enginetype: | V12 diesel |
| Cylindercount: | 12 |
| Maxspeed: | 98mph |
| Poweroutput: | 1000hp |
| Tractiveeffort: | 244252NaN2 at 34mph |
| Operator: | Missouri Pacific Railroad |
| Fleetnumbers: | 7100 |
| Retiredate: | 1962 |
| Disposition: | Scrapped |
AA was a designator used for several different diesel locomotive types custom built by General Motors Corporation EMC/GM with passenger or baggage space in the same body. This locomotive is listed as class AA-6[1] by R. Craig, and the designation is logical as the locomotive is described as "half an E6" in the Second Diesel Spotter's Guide.[2]
One such was a single locomotive built for the Missouri Pacific Railroad, delivered in August 1940, numbered #7100. MP 7100 was built for service with the Delta Eagle passenger train, which ran between Memphis, Tennessee and Tallulah, Louisiana. Note: Missouri Pacific ordered all their 'E' units with portholes instead of square windows like most of the E series from the EA to E7's. This was the only MoPac unit with square windows (on the baggage door).
Since the two-car train the unit would have to haul was comparatively light, the AA was built with only one 1,000 hp EMD 567 V12 prime mover, and a baggage compartment where the second diesel would have been.
Other EMC/GM locomotives carrying the AA classification include the Pioneer Zephyr, Flying Yankee, and General Pershing Zephyr power units.