Okay I'll bite; What's wrong with the trail gear kit, other then being a competitors product?
I don't have any real tech on why it's bad. But I will say that I have helped install one before and it's not that bad but pretty pricey for what you get, and the truck drove like crap after. Like OOPS said I have also heard the numbers are goofy.
To the op, what makes you want to do a 3 link in the rear rather than 4 link? Don't want to move the gas tank?