Well I just happen to have that same Shrockworks on the front of my rig. It weighs about 110-120# without a winch in it. The stocker weighs about 40-50# so figure on about double. As others have said the weight does not put additional stress on the actual driveline, but it will put some new weight on the front suspension.
I just got mine mounted up this weekend, for reference 1998 LTD 195k with all stock coils and shocks as far as I know, it has squatted the front end about 1/4" - 1/2" and I rub slightly when turning left with slight up-travel. I am positive it would sound terrible if I actual had the front flexed in a turn. I have a set of 99 Highlander coils that I am about to bolt on with a set of 5100s to give me a slight lift and eliminate the rubbing.
Now in your case, if the bumper does end up at 200# or more, then you WILL need something to help out the front out.
Good luck and post up some pictures when it is finished.