OK, guys. The flasher is made by Marshall and works with the Marshall regulators with the little round clear top with a black vinyl cap. The clear part shows green or red depending on propane/no propane. Some of the newer Montanas use a different regulator and this might not work on them. Here's a picture and a link.
I've been using this device since early 2003 and just moved it from our prior Montana to this one. The display/flasher mounts in the rig, location of your choice. The other piece replaces that black cap on the regulator. It has a plunger that fits down inside the clear tube on the regulator (there is a small hole on top of that tube). That plunger closes teh circuit when the red comes up (actually, I think the green drops, showing the red part). Anyhow, each of those two pieces has two wires. Run those wires from the flasher into the propane compartment, route of your choice. The kit also has two wire nuts. Connect the black wires then the white wires. The flasher unit requires batteries. It is either 2 or 3 batteries. AA I think but maybe AAA. They last 12 to 15 months, then replace the batteries. I can tell when they are low because the light comes on solid and does not flash when the propane is low. But it does come on and stay solid. Then I replace the batteries.
http://www.pplmotorhomes.com/parts/l...ator-valve.htm and scroll down to the "Remote LP Gas Indicator." On sale right now for $34.01 and shipping.