I don't know if the OP has an E350 or E450 (or chevy).
I had asked the owner of a RV rental franchise about replacing my old dual-arm mirrors with single-arm mirrors. The response was:
Don't replace your mirrors though. The two arm models were vastly better than the single arm mirrors. We never replaced the dual arm models, but I am installing new single arms every day it seems
Here is the main link:
http://www.am-autoparts.com/. It is the same mirror for the E350 and E450. They aren't heated, and don't have the turn signal on the mirror:
2002 - 2008 Ford E450 Van Mirror Pair Power Telescoping Dual Arm2002 - 2008 Ford E350 Van Mirror Pair Power Telescoping Dual ArmThese are my mirrors:
