Actually it does work as i have posted it in the past....It works great and has never failed me yet. you pull the thermostats out. fill the bridge back up with water. You dont need to pull the belt off. Start the truck, it will suck coolant down as it runs. it will eventually steady off. and then which ever side has an issue, will have small little air bubbles coming up from the side. with the thermostat housing cover off, looking straight down you can see easily which way it will come up from. If you want, you can squeeze a piece of cardboard in the housing from front to back and divide the two sides to make it easier.
Have to be creative
