I thought the transfer of wiring would be intuitive, but I was clearly mistaken. I have a heat pump with an aux electric furnace. Current connections are (by color)
X - blue
W2 - white
R - red
G- green
O - orange
Y - yellow
E - brown

Can anyone tell me where these should connect on the TH8320? Some seem obvious, but not all.

Pete Criqui

all wires should go to the same place except x may be L and white will go to aux

X may be common or emergency heat relay (suspect common)

Thermostat signals and wiring - Transwiki

The 8320 is quite a complex thermostat. I'd have to chase down both manuals.

E will be Aux heat

Never before have I seen x used as a common, X and L are used as a power to send the fault code to the t-stat from the defrost control. E is the emergency heat relay that has a wire on it. When used as a heatpump the 8000 t-stat has a termanal for w that says aux. somewhere on the stat has to be a C for the common wire. Also it is important you do the right installer setup for this stat or it will not work.

My reference:

Thermostat signals and wiring - Transwiki