Cornwell boxes have been made by remline, waterloo, and kennedy over the years. I have a Kennedy made 60 inch wide top and bottom with an end cab. However, as others have posted, Cornwell support for these boxes is non existent. If I need a slide or other part, I'm **** out of luck. I got a sweet deal on my set up so, when I wanted to add a side locker a few years down the road, the lack of support slapped me up side the head with a 2 x 4 when I was told no can do. I had no desire to trade my unit in on the current waterloo hencho en mexico units at great expense, I might add. Don't get me wrong, I like my cornwell box but, no support blows.
If I was out growing my current set up, I would: (1) Buy used (2) consider buying a Gladiator type two door wallocker with shelves and casters to store things I need but, don't use often. Think blow molded cases here. (3) Go through all of my tools to see what's taking up space that I haven't used in over a year, what I have 3 or 4 of, and anything else to thin out resulting freed up space in my current setup.
It's an older model (vintage) with friction slides.