Ed....Those cases are Medical transport cases and as stated above come in quite a few sizes and variations. They are all standard in width and length (19.5" x 31")
The ones with a flat lid come in either Small @ 7.5" in Height or Medium @ 10.5" in height.
The Large @ 17" an X-Large @ 22" come with storage lids and are much larger and unless your storing really light items can be to heavy to manage easily.
Hers a Pic of the Small container
This Pic shows the Medium, Large and X-Large containers.
The Insert is ment for the Medium container but should fit the base of the Large and X-Large as well.
They fit perfect in the rear of the Pinzgauer. I'll be running 4 on the Left side and 4 along the Right side. 3 will sit in the center well and provide the platform for my bed.
I can highly recommend these cases, as I have used them for storage for years. I currently have 11 Mediums 1 with the Insert and 5 Smalls.
I purchased them from many sources, Colemans Surplus, eBay, and local Military Surplus stores. On average expect to pay $60.00 each plus shipping so try to find them locally as shipping can run up to $50.00 each sometimes. Many places are out of stock right now but new supplies hit the market from time to time so just keep looking.
Miles