A few changes from other versions I've seen. This fly has a pretty large wing and using it as the hackle post would create a bit of bulk (as well as a bit of a challenge to seat it properly when pulling over the thorax; using Uni-stretch as the post provides a stable base for wrapping the hackle and although it adds a step, simplifies the tying process. Lots of steps, but basically a pretty simple tie. Shown here as a (western) Green Drake; change colors to suit your needs.
hook - Dai Riki 135 #10
thread - MFC 8/0 dark olive
shuck - Zelon amber/mallard dyed brown
rib - Sexi-Floss brown/UTC wire amber small
abdomen/thorax - dubbing olive
wing - Congo Hair black
post - Uni-stretch black
hackle - grizzly dyed olive (Hacklestacker style)
Part 1
mash barb, start thread; tie in shuck, fold/wrap to bend, trim
measure (shank length) some mallard; tie in on either side of shuck, trim butts
tie in wire & Sexi-Floss
dub thread, dub tapered, robust abdomen to about halfway between hook point and eye