GE Dash 8-40B

{{More footnotes needed|date=October 2021}}{{Infobox locomotive

| name=GE Dash 8-40B

| powertype=Diesel-electric

| gauge={{Track gauge|ussg|allk=on}}

| image=UP1869.jpg

| caption=Union Pacific Dash 8-40B #1869

| builder=GE Transportation

| buildmodel=Dash 8-40B

| aarwheels=B-B

| builddate=1988 – 1989

| totalproduction=151

| locale=North America

| operatorclass=B40-8

| poweroutput={{convert|4000|hp|kW|abbr=on|lk=on}}

| primemover=GE 7FDL16

| operator=Various, see list

}}

The GE Dash 8-40B (or B40-8) is a 4-axle diesel-electric locomotive built by GE Transportation between 1988 and 1989. It is part of the GE Dash 8 Series of freight locomotives.

A total of 151 examples of this locomotive were built for North American railroads.

The GE Dash 8-40BW (B40-8W) is a variant fitted with a full-width cab. Another variant is the GE Dash 8-40BP, more commonly known as the Genesis series. The locomotives in the Genesis series are the P40DC, the P42DC, and the P32AC-DM.