I am trying to elevate some older passenger cars buy adding on more details and painting. I want to add some roof vents for the kitchen car, and I want to add some diaphragms between the cars. At some point I want to update the lighting. Any suggestions on resources would be most welcome. -Peter
You probably would get even more precise replies if you were specific about which "older" cars you wish to upgrade.
For lighting, many, many folks here use the products offered by Gunrunnerjohn, who is a very active member of this forum who does not, to his credit, "push" his products which are sold through Henning's Trains:
Scale City Designs, Walthers, Precision Scale and Union Station Products all make diaphragm kits. Though it sound like you're updating older heavyweight passenger cars I would love to see O scale full width diaphragm kits for streamlined passenger cars. Union Station makes end plates for full width but curtains are not included. Union Station should also have the other parts you are looking for. Check them out.