Installing Honeywell thermostat

I'd like to do this install and have selected the Honeywell RTH7600D thermostat with the auto changeover function. My MH has the Coleman Mach III a/c and a suburban furnace with the following wiring; a 2 wire Red and White, a five wire Blue, White, Green, Yellow and Red and a single heavy white wire three times larger than the other wiring.

The MH to current Coleman thermostat is as follows:

MH -------------------------- Current Coleman T
2 wire Red(-12vdc(verified))-------to White
2 wire White(+12vdc)---------------to Red
---
5 wire Blue(and large gauge White)-to Blue
5 wire White-----------------------to Grey
5 wire Green-----------------------to Green
5 wire Yellow----------------------to Yellow
5 wire Red *Not Used
---
Large white copper threaded wire --to Blue

How does this cross over to the Honeywell?

MH----------------???-----------------HW
2 wire Red(-12vdc(verified))-------to White
2 wire White(+12vdc)---------------to Red
---
5 wire Blue(and large gauge White)-to Blue
5 wire White-----------------------to ???
5 wire Green-----------------------to Green
5 wire Yellow----------------------to Yellow
5 wire Red *Not Used
---
Large white copper threaded wire --to Blue

Thanks,
Sam