Larry:
I use Findster.  It is very good up to about a half mile. I also use an old Garmin Astro 220 with DC 30 as a backup if they are going to go out of range of Findster.
I have had to locate them with Garmin, then drive close enough to pick them up with  Findster.  Both are “Live Tracking” so I can tell where they are heading.
My Garmin setup has a range of a mile or so but not near the map detail.  It is 10-12 years old and the newer models are much better but cost over $1000.
Coach
_________________________
"Filet that fish?  Hell naw!  I'll scale him, gut him, fry him up in grease, take him by the head and tail, and play him like a French Harp!" - Uncle Paul sometime in the 60s.