Questions answered:
this is the paint I use for letterboards, or to overspray an entire car if it is too glossy.
Some aluminum cars have an unrealistic high gloss finish…especially the plastic ends on a K-Line car.
These roof vents are a good solution for Budd cars. They will need a bit of sanding to get rid of mold joints, and I clipped the mounting stud shorter as to not interfere with interior lighting strips.
Re: better diaphragms. The Lionelsupport.com web pages feature a variety of diaphragms. Another extensive project I am working on is a Frisco METEOR passenger train, and the TEXAS SPECIAL aluminum cars being redone for the project have full width diaphragms. Full width was not what I wanted so I bought TS complete car ends from Lionel support as replacements and diassembled the full width ends and saved the parts…then repainted them silver. This involved a bit of dremel work to make the striker plates correct.
Hope this helps.