question about tailshaft..

is it necessary to unbolt the torque arm to remove the tailshaft? i've been working at this bolt all night, doing pb blaster, liquid wrench, everything i have, heating, hitting it with a small hammer, trying to tighten and then loosen it, just nothing is going. i'm trying to get the tailshaft off so I can swap the speedo gear on the output shaft.. i tried getting the tailshaft off with the torque arm still attached to it, no luck or i'm just a pussy... any tips?