Shop manual and EVTM don't say what the fan dropping resistor value is, so we'll have to measure it, and it's going to be substantially less than 1 Ohm, been down this road before with some other dual speed radiator fans. Measuring really low resistance values is hard, because meter lead and contact resistance flummoxes the measurement, I have a 4-point Kelvin probe ohm-meter, a fairly spendy HP unit, but we'll do this another way.
I made some measurements this morning, pulled the Hi and Lo fan relays and measured the stabilized motor current.
Hi fan = 14.5A
Lo fan = 10.3A
Since I didn't feel like pulling the lower shield and measuring the voltage drop across the resistor, we'll derive it another way.
Battery voltage at the time was 12.5V, so...
12.5V/14.5A = 0.86 Ohm
12.5V/10.3A = 1.21 Ohm
So in low fan mode there is 1.21 - 0.86, or an additional 0.35 Ohm in series with the motors, so the fan dropping resistor is about a 1/3rd of an ohm
Power in a resistor is I^2R, so 10.3A^2 X 0.35 Ohm = 37 Watts.
Good rule of thumb for power resistor derating is 50%, so I'd look for ~0.33 Ohm, 75 Watt resistor.
This one is close, but the power is a little low, 0.33 Ohm at 50W:
http://www.digikey.com/product-detail/en/9-1625984-7/A102447-ND/2366305