I just replace the ant. mast of my '94 yesterday (wouldn't full retract). I was not patient enough and almost screwed it up. I only saw a cable, off white and a couple mm in diameter, that screws into the antenna mast assembly.
I don't know if the FJ80 has the same mount, but what I did was:
1)With masking tape wrapped pliers, I loosened the ant. nut.
2)My arms are long enough that I could extend the ant. and hold on to it at the same time. Otherwise a second person or some other mechanism to prevent the antenna from falling and scratching the body.
3)Using two pair of needle nose pliers, I loosend the little nut (part of the antenna mast assemble that screws into the cable) from the cable, then unscrewed the rest of the mast.
4)Reverse order with the new mast.
I wish I had not been so impatient, it would have saved me some time. I had hoped for better reception, but alas I'll have to settle for an antenna that fully extends and retracts.
Good luck
Ross