I do not own a T-3
all systems operate the same.
Never hold the wire more than 1/4" from ground or you may spike the engine controller.
Invest $8.00 in an adjustable spark tester.
Before you condemn the coil verify...
1)Coil control is present at both coil drivers.
2)Ignition Wires are not open or shorted.
As far as swapping a coil from another vehicle as long as it wires/operates the same and primary resistance is the same you can swap it, anything different may/will damage the controller.
You have a 4 terminal connector with 3 wires...
Cavity #1...DB/YL Coil #2 Driver
Cavity #2...BK/GY Coil #1 Driver
Cavity #3...Not Used
Cavity #4...DG/OR ASD Power Input