I bought 5 of the Jackson sharp open air cars(not knowing they'd produce another version later on) and I haven't had the foggiest idea on what to do with em...until yesterday.
(https://scontent-iad3-1.xx.fbcdn.net/hphotos-xfp1/v/t1.0-9/11754245_917474384942685_4569337453831798996_n.jpg?oh=58025e6ee89126ba9a5ed0f34790d410&oe=564BFD45)
B&O Switcher pushing the cars into the shops
(https://scontent-iad3-1.xx.fbcdn.net/hphotos-xap1/v/t1.0-9/11201846_917489194941204_2046752498870073816_n.jpg?oh=da21d34a577cea87706cfd4e4fe96ba1&oe=560E40E7)
So far so good
(https://scontent-iad3-1.xx.fbcdn.net/hphotos-xta1/v/t1.0-9/11143468_917543864935737_1786764032195006284_n.jpg?oh=1c6a3fe8b3de3be8430be5d20e4f8eb1&oe=560EE9E2)
About to enter the paint booth, thinking about fully enclosing them with window glazing instead of leaving em open as originally planned.
http://www.nps.gov/muwo/learn/historyculture/upload/MtTamMUWOrrIDP.pdf
https://www.google.com/#q=mt+tamalpais+gravity+cars&imgrc=9yhNZ71Eqt6s1M%3A
https://en.m.wikipedia.org/wiki/Mount_Tamalpais_and_Muir_Woods_Railway
This page has a video of the actual gravity car ride, albeit in the roofless cars that were also used.
http://foundsf.org/index.php?title=Muir_Woods_by_Gravity_Car
the 4 that i've done(i'm saving the 5th to for a before and after shot, then that will be modified) will be assigned to Strasburg RR. I have 4(out of 6) that were factory made for Strasburg itself. I also have a baggage and 2 combines being painted up for Strasburg. I also did an engine.
(https://scontent-iad3-1.xx.fbcdn.net/hphotos-xfp1/v/t1.0-9/10432116_988504831182985_1795525453587808825_n.jpg?oh=bac6416ab8e9743d037048a1f92567a5&oe=56529628)
You can see the engine and one of the cars here.
I did something simular to that with a Athearn Obs. I made 1/4-1/3 open (Obs deck end) and the rest was enclosed.
If I may ask, what material did you use for the sides? I might be interested in doing this as I've been looking for mid size passenger cars to use, but didn't want to use "old time" cars.
Styrene, I used the Evergreen stuff. I did two 2-plank sections, and a 1 plank section.
I'm currently on break from model railroading however, these cars got to me a bit as I can't seem to finish painting them. evertime I think "Finally i can decal soon" i find something i missed, or the paint comes off when i peal off the masking tape.