nicodex_

About the 371 Motorized Truck. The outer box I was familiar with is marked "MFG. NO. 463711", but your box has "MFG. NO. 3463711". Curious about the extra digit.

I'm late saying this, but the item you have is probably something along the lines like this: As you say these boxes were sold to stores who were then meant to sell the cars individually to their customers. If underneath the garages they have a red sticker with "Made in Denmark" written, then they were imported by Samsonite and were meant for the North American market. LEGO dealer boxes like these are quite collectible, so you have something valuable.

Having occasionally scanned catalogs myself, it's a surprising amount of work. Thank you for taking up this project!