Wish I had seen a thread like this long ago. I had no idea my 2010 E350 mirrors could extend. Drove it for the last 8 years in ignorance, even when towing my raft trailer. Then just recently I hooked one on a low hanging juniper limb, and the juniper kindly extended the mirror for me while folding it back.
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2010 E-350 4x4 Sportsmobile "Moby" for the backroads
2109 Sprinter Pleasure-Way XLTS "Pequod" for the highways
www.mobygoes.com