At the posted coordinates, look for a wooden post with a little black plaque at about hip height. It says City of Nepean on it -- a bit of a relic, eh? At the bottom of that plaque, look for 4 digits and call them AB-CD.
From there, make your way along the trail down the hill to the bridge at N 45° 20.133′ W 75° 47.396′ (see waypoint). There's a small plaque on the right side diagonal with manufacturer information. There are five embossed (bumpy) digits -- call them BBEFD, and four stamped digits with a vertical pipe character -- call them A|DGC.
Enjoy the view! Geokid and I saw and heard all sorts of birds while placing this cache.
The final coordinates for GZ are N45 20.DFF W075 47.E(A-G+B-E-F)D. Please don't spoil the hide type in your posted photos.