This version of the Trico Spinner has been a mainstay of my box for more seasons than I can recall. It ties easy and fishes even easier.
For a full tying video, click on the link below:
Ralph,
Nice video; thanks for posting it. Tricos on the Missouri are a bit smaller; I gave up on standard hooks for that hatch and tie parachute duns and spinners on a #20-22 emerger hook (Dai Riki 125) to get more gap clearance. My eyes (and casting) are worse than yours, too; I started putting a hot pink Mcflyfoam indicator on my spinners.
Regards,
Scott
Scott, I hear you on the eyesight…I’m right there with you. Indicators on my ant patterns and some midges these days. May be a good idea on this pattern as well. 
On my blog the pattern is listed as #18-22. They vary here too. But I usually begin with the #18 since I can tie them on and see them better. Most of my Trico fishing is smaller water and stalking. So that helps on seeing my fly a little bit too.
This poor eyesight thing must be going around. I hardly ever fish a very small dry alone anymore. I almost always use a slightly bigger dry as an indicator with it. The indicator fly does seem to be getting larger and larger lately, though.
Joe