The passenger side tow mirror has flat glass and not convex. I like convex. I see much better while backing up because it gives a much wider view angle. My brain adjusts quickly to the variants in sizes caused by the convex glass. As is the flat glass doesn't give me a wide enough view angle both side to side and up down. If your van is 4x4 or otherwise lifted then the narrow view angle is more apparent in the up down dimension. Set it at ride height and I can't see the small cars next to me, set it down low and I can't see far back. The convex mirror solves almost all of the viewing problems for me. For the rest I use a 15in wide angle rear view mirror. This works for me because both of my vans are passenger vans.
I went to eBay and purchased one of these: http://www.ebay.com/itm/NEW-Mirror-Glas ... c2&vxp=mtr
I thought that I could use 3M double-stick tape but since the glass itself is also convex that wasn't possible without a lot of work. My solution is to use caulk. Pop the glass out from the housing then lay it flat on a counter. Use a generous amount of caulk and let it set overnight then pop the entire mirror portion back into the mirror housing. Now I can see all that I need to with just a quick glance and it has a factory look to it.
(Yes, the upper flat glass assembly pops out without any tools. Popping it back in can require 3 hands and a needle nose plier but is easily doable with just 2 hands and a needle nose plier. If you never popped this out before there are 7 things you have to line up before popping the mirror back into the housing. 2 of them will need assistance from a needle nose plier.)
My other van has the 2 piece smaller mirrors. For whatever reason the passenger side upper glass is convex from the factory and I can see easily.
Hope this helps™,
06 E350 RB
06 E350 Quigley V10