I am installing cab/roof/running lights on my truck. I was told they have to be amber. Is this true?

 

Most likely true. Most states have similar (if not identical) laws regarding lighting. Any runninglight visible from the front of the vehicle must either be a legit headlight or DRL, or beamber in color. Any running lights visible from the rear must be red. Rear turn signals can be either amber or red. If they are amber they can not be lighted when your trun signals are off.

Take a look at a tractor trailer next time you see one at night. Forward facing lights are amber, rear facing lights are red. Even 3500 pickups with lights on the dually fenders follow this convention.

Some more useless information in canse anybody was wondering:
Fog lights must be amber or clear, and can only be used in conjunction with running lights and/or low beams. Driving lights can be amber or clear and only used in conjunction with high beams. Any auxilliary lights (roof mounted light bar for trail lights) must be covered when driving on roads.

This is what I've picked up from myself, family and friends beingpulled over for various violations.