UP number boards question

[scratchy]

quick question, i was looking at the JR UP sd40-2 and noticed the number boards on the rear aren't used and instead the road number is printed above or below it, why did they do this?
Just wondering
Heres a pic of what i mean
http://img835.imageshack.us/img835/2143/p5021949.jpg

 

[505657j]

That is also something I have always wondered

 

[SD45T-2]

To save money.

All the number boards are lit, and if you can not light 2 of them, you save a bit of cash, which lowers the railroads cost-per-car mile.

 

[rgcx]

Also, if a numberboard is broken out, the FRA can place a bad order tag on it until it's repaired. Thus, the rr loses a working unit due to a minor infraction. Additionally, all numberboards must be able to light up or that's a bad order defect too.

 

[scratchy]

Huh, interesting, so it was all about the money.. of course, cheers for the answer guys