I'm not necessarily going to make a recommendation, but I'll play the black sheep role nonetheless. My truck had the usual 2nd gen steering slop and I opted to buy and install one of those "steering stabilizers." I will say that it tightened up the steering considerably. I have had my steering box looked at prior to this and it is pretty much used up to the point where it can't be adjusted and it does leak a little. Also, my truck has always pulled a bit to the right. I purchased the stabilizer because at the time (and my then ****ty job) it was the cheapest route to go to "fix" the problem.
So, with a good steering box and an alignment, I'm not sure how effective a stabilizer would be. I think that it'll either help or do nothing at all. I'd say fix/replace everything involved with steering and get a good alignment first. Afterwards if you're still not happy, consider a stabilizer. If you're STILL not happy, consider that our trucks use a pitman arm setup rather than a much slicker but more expensive rack and pinion setup. In other words, you'll have to deal with it, LOL.