I know I am going to get flamed here but no, I did not use friction modifier. I have a friend who works at the ford dealership and he recommended I didn't use it. I cannot remember the reason behind it but I took his advice. I haven't had any problems so far and it has been a few years.
Again, don't flame me here guys....By what I remember (and could be totally wrong) something to do with the modifier allowing the clutches in the rear to slip, thus alleviating noise from the rear.
Good luck with that. I had him do mine last year. That was quite a waste of 10 hours, a set of gears, and $200 for the install. All had to get torn out and redone by a real professional a few months later. Thank god it didn't blow up while I was driving it. :nono:
IDK about the lucas...only stuff I ever used. I had the gears installed 3 years ago and just started to make some ticking noise while slowing down/ making turns recently :nono:.