Athearn did it. The new SP cabooses they made came with a decoder or without. The models WITHOUT the decoder had the marker lights but NOT the interior lights! They needed to be wired to a resistor and then to the track to operate also. This is why I ask!
The LEDs are integrated in to the decoder board which is on the roof of the car for the Sp cabooses. Soundtraxx made these decoders and they are also making the decoders for the Metros.