Need for the pre IVR resistor

[cosmo115]

I was wondering if anyone knows the story behind the little pre-IVR resistor installed in 65 and 66 Custom Cabs (perhaps other models as well). I measured 1.3 ohms of resistance. Is this thing supposed to protect the IVR? or compensate for the same IVR being used on trucks and cars as well?
I have since installed a solid state IVR, and have not reinstalled the resistor....dont know it that was correct. thing to do (I have a picture of it but can't upload it into this message)
thanks
Cosmo