I bought a cargo van. Windows in the back doors and slider door. I added CRL windows all around. I like the feeling of openness in the van with windows all around.
In the back area I put up walls the full height of the van. I glued black felt to the plywood where it came up against the window, so from the outside it just looks black in that area.
I think the black tinted glass offsets the large masses of steel on the outside, so I did it for looks too.
Note: on my 2014, I discovered that the factory window tinting is lighter than the CRL tinting....Discovered that when I looked at RD's 2015! Newer (than 2014) vans seem to match the tinting.
If you want a window van, and don't plan on installing the windows yourself (as I did, not too hard to do) I would buy it with windows already in. It's cheaper than paying for the windows from CRL plus the labor to install.
I haven't been in a factory window van so I'm not sure if the CRLs are direct replacement on the sides. The factory windows have a split section in the back side windows that the CRLs do as one piece (at least on my 159WB.) Also not sure if there is any additional trim provided around the windows on a factory window van... worth looking into.
Pics of the install in my build thread below...
Ed
ps. On the Transit, the window van low roof, is the ugliest thing on the road! Those tapered windows look like someone stepped on the back of the van and squished it!