[Philippe Jeanneau]

All very interesting points, and very happy to see another photo of the smaller channels... It totally makes sense that they would exist, as did the larger size. As to how to properly carry them without loss and having them rattle their way down the road is another matter...

I believe that we were trying to ascertain the original dimensions of the larger size channels... While looking for this answer, I thought that one big clue would be in this first photo... If you compare it to the diagram, these should be as wide as the distance between C and B in theory, except...

1- We don't know if the truck in the photo has the bed in the diagram...

2- We don't know width of the channeling that surrounds the box...

But could come close... The difference between C and B is 15-1/8 or 384.17 mm which might just be the ticket and what my friends Chuck, Bob and I came up with...

As for the length, somewhere in the 81" or 6.75' seems in proportion...

I know there are some out there, but someone willing to help has to come up with the information...