Yet another thermostat upgrade question

I purchased non-programmable Honeywell thermostat and still confused on how to connect it in my Heartland Wilderness 3150DS.
The model of the new t-stat is RTH5100B.

There are 6 wires in my TT connected to Coleman-Mach analog t-stat. I decided not to install additional switch for Hi/Low fan operation to simplify the installation. I can always add it later as long as I can identify all the wires.

Here are the wires that are coming out of the wall.

Red
Yellow
White
Brown (Connected to Grey)
Green
Blue

I know I need to connect White and Yellow but I’m really confused about the rest of the wires. Some posts saying not to use Blue and Green others are saying not to use Red.

The new –t-stat has the following connections:

Rc
R
Y
Not used
W
G

I would appreciate any help with this mod.