Dave Nelson asked about the roof. Is it well documented?  Yes the 6000 series car is very well documented, with numerous paper plans. However I do not have these all scanned.  And like much research, come from sources claiming a copyright. (Dubious copyright claim or not, I uniformly honor those claims as I do like researching at the sites. And in my experience with some, yes they can and do track use.)  

       Of a factory fresh interior shot of the 6000 series cars. None was in the builder’s photo folio. I stated that I know I have a photo around somewhere however it is not at my finger-tips at the moment.

The car number of the interior photo: Please re-read my prior post, forth sentence from the end in the post. I was quite clear on what car number the interior photo was and gave it as 4982. On outside dimensions, the cars are similar in dimensions, with the 6000-30000 series cars having fixed ends.

Yes the 4982 does have an end door as you can see. Could explain the photo in the folio.

  The roof design plans are largely the same design regardless of box car series. I say largely, however not identical.  

 NP stock cars with radial roofs are different.
   This series of NP stock cars 80000 – 80049 were leased from Mather Stock Car Co, and do have the circular roof, however different interior bracing.
                                                                                 
                                                                                                                                          James Dick    Roseville, MN 

or is that well documented elsewhere?

Hey guys it’s that time of year!

Are you ready for a great show? Come one come all to the Eastern PA 2 rail O Scale swap meet and train show Saturday October13th, Doors open at 9:00 am. The show is over at 1:00 PM dealers will be open until 1:00 PM Admission at the door is $5.00 Wives, Children, and Active Military with ID are free! Come enjoy good Lancaster County hospitality and Amish style cooking. No smoking on the premises. Visit the Strasburg Railroad, Pennsylvania State Railroad Museum, or spend a night at the Red Caboose Motel. If you would like a table please contact us off line ( oscale48@... )
Please share this and forward  to your friends.

Location: Strasburg PA Fire Company 203 W Franklin St. Strasburg PA 17579 https://www.google.com/maps/place/Strasburg+Fire+company/@39.9815868,-76.1832858,17z/data=!4m7!1m4!3m3!1s0x89c63a1c210dcfdd:0x2de668e25b2419f0!2s203+W+Franklin+St,+Strasburg,+PA+17579!3b1!3m1!1s0x0:0xf055ac77944cae3d?hl=en

Sincerely,

Rich Yoder

John Dunn

Cleveland Tractor had a connection to the White Motor Company.
https://case.edu/ech/articles/c/cletrac-inc

From the text details below the image, this is a 1927 photo. It's interesting to see a Northern Pacific automobile car loaded in Cleveland, Ohio, and routed east. 

Eric Hansmann
Murfreesboro, TN

I've reviewed many of these historic Lackawanna images and they seem to fall into a few categories. 

First, many images document an accident. The images of the NP boxcar with the Cleveland tractors are typical. Many seem to document a worker injury or a fatality. I can't tell you how many I've seen that illustrate a crossing and the crunched remnants of an auto.

Second, many images document new facilities, especially passenger stations.

This last point took awhile to figure out. There are quite a few images of homes and pastoral scenes. I think these document property the Lackawanna needed in order to upgrade their right-of-way.

At any rate, we are fortunate that this extensive collection survived. I am not familiar with a similar railroad company photo archive. Barriger's images come close but they lack the subject focus of the Lackawanna images. 

Eric Hansmann
Murfreesboro, TN