Try 411.7375 which is used in Prescott-Russell. Last winter sitting in a restaurent in Plantagenet, a repeater
just across the road kept triggering Close-Call on my scanner, and it was snowing; activity in french. I'm not sure
Rockland proper uses this system but check it out.
Also check 154.100, not sure of its status but also licensed to Prescott-Russell. You won't find it in a
search for Ontario as repeater is located across in Quebec at Ripon.
Good idea to look at vehicles to see what band of antennas they're using. The older style UHF are either short
quarter-wave (4-6") or stacked with loading coil. Newer-style UHF is single element half or 5/8 wave with base
loading coil and conical spring. For those who don't recognize certain antenna types, well we all started somewhere...
As for UHF DMR located at Rockland, may be worth a check but I'm a bit doubtful they would need to join a
wide-area system, but you never know.
This is a handy site for quick checks, though I believe the database is a year old. You can try
any name combinations such as Rockland, Clarence-Rockland, Prescott and Russell etc.