My tow vehicle is a 2007 (classic style) 2500HD. It had standard mirrors on it and I got after market extendable mirrors with the little tear drop wide angle lens in outward lower corner.
On the road these mirrors are fine for checking lane changes but watching where rig is while close to mail boxes etc is hard to determine. First trip out was 1500
miles but I wanted a 6" convex mirror like the 18 wheelers have (and my previous two pickups) but I could not locate one to clamp on the 7/8" OD stainless rails that are exposed when the extendable mirrors are pulled out.
I was at truck specialty shop last week and got a 6" convex and an extension arm figuring I would have to fabricate one. Did so today but wound up not even using the 8-14" extension arm I also bought.
Was thinking of how to do it and spotted the answer and one thing led to another. I found a U bolt 1 1/4" inside with 1/4X20 threads. The convex trucker mirrors come with a L bracket.
I located hole locations in L bracket and drilled an extra hole in it to take the U bolt. I turned a round piece of stock with OD to just fit inside U bolt ears and bored a 7/8" hole in it to go around the mirror arm. It is about 3/4" long. After drilling 7/8" hole I cut the round stock to have two halves that fit perfectly around the 7/8" mirror arms and taped them in place with Scoth tape.
Next I took a piece of stainless rod stock about 1/2"x1.5"long and drilled it and tapped one end about 1/3rd in the same thread as mirror has. On the other I threaded 1/3rd with same thread and was ready to mount. I mounted it on lower bar and the two part sleeve protected the mirror tube from damage when I torqued down the nuts on the U bolt. I don't think it will move as the base of the L bracket started to conform (bent) to the mirror arms.
The result is the 6" convex now allows me to see all the way from passenger door handle and outwards at least a 40 degree angle (much wider that tear drop mirror allowed). The convex mirror is on same level as extendable mirror so blocks no vision out the right.
Went and got two more U bolts and am going to mount another convex on driver side in the same place when I get by the truck specialty store next week.