You will have to buy and weld on trailing arm axle perches which a few places sell them and the track bar mount on the axle you need to cut off the old one and weld on the new one.But if your looking to lower the truck you need a adjustable track bar so look in to that part see if it uses the factory mount or comes with one.Take a look at
http://67-72chevytrucks.com/vboard/s...d.php?t=550878 he did the same thing just used a bigger rear end.