The bottom mirror section of one of the manual Velvac 2020 mirror heads on my 2003 (installed in 2004) snapped off the mount; no "re-snapping" effort worked. I decided to replace both mirrors (both had started to "de-silver" in spots), and ordered replacements from Mill Supply; this is the "left hand" mirror head . The "right hand" mirror head is #714580, and is pictured on the linked page below this one:
Left Deluxe Manual Mirror Head - 714579 | Mill Supply, Inc. (https://www.millsupply.com/deluxe-mirror-head-bt-714579.php?p=9878&cs=596+3351+446)
The mirror heads came with adjustment "collars", but the collar needed for my application was plastic; I re-used the metal collars (with the "guide button") from the original set.
The heads and mirror sections are not adjusted yet; that will take a lot of hopping in and out of the cab with the 3/16" hex head, and the rig is not moving out of its space today. (Neither am I.) ;)