Conversions
In some cases, a B unit is converted from an already existing A unit. The cab is either removed or has its windows blanked out (such as on CSX GE BQ23-7 units), and all non-essential equipment is removed. The degree to which this equipment is removed depends on the railroad, but may (and usually) include the removal of the speedometer, event recorder, horn, headlights, toilet, and cab heaters. This conversion was sometimes performed when the A unit had been in a collision and rebuilding the cab was not cost-effective. In some rare instances, B units were converted to incorporate a cab, such as on the Chicago & North Western Railway in the 1970s with some EMD E8B units bought from the Union Pacific. The homebuilt cabs were referred to as "Crandall Cabs." Also, the Santa Fe rebuilt four of its five GP7Bs to GP9us with cabs. In the Illinois Central Gulf's GP11 rebuild program, some of the engines used were ex-UP GP9Bs, and in their SD20 program, some ex-UP SD24Bs were also used.
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