Make about six or seven turns of 0.015 lead wire on a size 14 TMC 3769 and break the ends off, leaving the fly weighted but not heavily weighted.
Tuck the lead a couple of eye lengths back from the hook eye, start the red 14/0 thread in front of it, and run back over the wire all the way to the bend.
Clip a small clump of fox squirrel fur off a straight-cut edge of the hide, treating it like elk or deer hair, thin it down further, and bind it in as a sparse tail. The ragged guard hairs put it closer to a full shank than a half.
Wrap forward over the tail butts, bind in small gold wire just behind the lead, and wrap back over it to the base of the tail.
Wax your fingers and dub red fox squirrel belly fur down tight on the thread. Use the bare thread to work back so the first turn of dubbing lands right at the bend, then build a tapered abdomen forward - the lead already builds in some of that taper.
Clean up any stray guard hairs, then spiral the gold wire forward over the abdomen in evenly spaced turns, tie it off with a couple of thread wraps, and helicopter the end off.
Form a short dubbing loop at the very front edge of the abdomen, binding it down with thread, load it with a small pinch of the spikier grey-brown back fur, spin it up, and sweep the fibers back with a dubbing brush as if folding a hackle.
Wrap the loop forward three or four turns for the thorax, sweeping the guard hairs back after each turn, then tie it off behind the eye and nip the thread out of the loop.
Strip the butt of a Hungarian partridge feather and create a separation point at the tip. Tie it in by the tip with the inside of the feather toward the hook, then fold the tip back and put another turn or two over it.
Give the stem the slightest fold, take one turn of partridge for the collar - one is usually enough - sweeping fibers back off the hook eye, then trim the stem out.
Whip finish three or four turns with the red thread. Pick up a drop of Solarez Bone Dry Plus on a dubbing needle, run it up and down the thread and make a few turns with it, then unwind those turns so only the head is coated and no resin reaches the hackle or dubbing, and cure it with a UV lamp.