The Casco low coolant sensor finally arrived and I installed it today. Am happy to say that it works great. Just like Stuhly said above. I am glad I ordered the $70 Casco sensor rather than the $280 sensor from Monaco (Allied). Hope this will help someone else save $$$.
Thanks again to all who contributed on this thread and helped me make the decision to go with the Casco sensor.
PS. The old sensor had a crack in it - no doubt this was causing the intermittent problem.