6-wire system vs. 5-wire thermostat

[mbct451]

I have an oil-fired forced-air furnace, with AC but no heat pump, controlled by two master/slave thermostats for two damper-controlled zones. The master stat has 6 wires (R, B, O, G, Y, W) running to a Honeywell T87Y thermostat. My burner tech recommended a Honeywell RTH6300B replacement, but I see no way to wire that up and have heat, AC and both zones operational. Honeywell seems to be MIA both online and via the help line, but based on a few other posts here it looks like this model will not work. Can anyone either (1) tell me how to wire up the RTH6300, or (2) recommend a suitable replacement? I'm amazed at how difficult it is to get answers from the manufacturers other than "Call a contractor".

[Rblack230]

I think this might help...order a Honeywell programmable thermostat # TH4110D1007 on line (only) which has the right connections.