SDL39
Three quarters of the Alabama Midland Railroad (AMRR) heritage short lines and branches were composed of Class 3 and excepted track at its start up. It did have the well-maintained former CSX (ex-SAL) secondary main known as the ” Bow Line” from Montgomery, AL to Thomasville, GA where the large SD six axles roamed. Much of the routes feeding into the Bow Line were light rail or possessed bridges banning the heavy SDs. While suited for first Generation four axle road switchers, SD units allowed longer trains with better tractive effort while spreading the load on the sometimes less than opportune trackage on these branch lines. A group of ex-MILW SDL39 units were orphaned after the SOO-MILW merger in the early 1990s , as parent Canadian Pacific Railroad saw them as odd units in a combined roster built on standard 38 and 40 series locomotives. AMRR quickly acquired them for use on the gaggle of branches it referred to as the Georgia Grain Unit in South Georgia and Alabama. These units were actually designed for export, were lighter than an average GP38 and had the added extra axles to spread weight and increase tractive effort. Special light loading six axle export trucks balanced reduced weight and spread-out tractive effort but made them an anomaly in Class One railroading in the 1900s and 2000s.
A total of nine units came to the AMRR, with the tenth unit wrecked years before while working for original owner MILW. After a thorough rebuilding, the units were assigned to the former Georgia Southwestern Railroad (GSWR) and Atlantic & Gulf RR (AGLF). They primarily hauled grain and agricultural products on light branches, much like they did for MILW in the 1970s-1980s.
| Road Number | Number Of Units | Paint Scheme | Notes |
| AMRR GSWR AGLF | 9 | Various Schemes | exx-MILW, ex-SOO: purchased for use on AMRR,GSWR and AGLF light trackage; |
Georgia Road Transportation 