I bought a K-Line Red Cross passenger set which was produced at the time right after 911 with all the proceeds going to the 9/11 victims and all who were affected by our nations terrible tragedy. This set hit a cord with me and I had to have one. The 3 car set was not produced with an observation car just 3 red couches. I'm the kind of guy that needs to have something at the end of the train like a caboose or observation car. I still think the end of every train should have a caboose but that's another post! 
I got a package of LED holders from Evan Design to try out on one of the coaches. I got the holders that would work for a 3mm. bulb. I measured and drilled 2 11/64 holes for the holders and slipped the 3mm bulbs in then hot glued everything in place. I used heat shrink to put all the wires together and soldered them in the overhead lighting. I plan to make a Red Cross drum head and put that on the back in front of the red Cross worker standing by the vestibule opening. Here are some pics to give you a better idea how I did it. Pictures are not perfect I wasn't using a flash. Here is a link to Evans web site to see the clips better. I even got this cool scale ruler card as an unexpected bonus! Thanks Evan Design! Great product.
http://www.modeltrainsoftware.com/3mm-led-clips.html
