MSP District 2 Unit Identifiers

[kd8ati]

So anyone who listens to MSP Detroit on a regular basis is familiar with the 2xxx series unit identifiers. However lately I have been hearing what sounds like "district xx" unit identifiers. For example tonight I have heard station 20 calling what sounds like district 12 & district 10 road units. Am I hearing this correctly, or am I just way off base here? If I am hearing it right, what are these units? Why are they not using the standard 2xxx identifiers?

 

[hazard78]

They are units assigned out the District Headquaters in Taylor. Most are motor units.