Just saw you were from Missouri.
Look around on the Suspension Section with the search feature.
This question is a very common one.
It's also a great update to your truck.
(I highly recommend it)
I typed in "disc conversion" in the search box and came up with 4 pages of threads.
Check them out here:
http://67-72chevytrucks.com/vboard/s...archid=1885930
Type in "drum to disc" and you will get plenty of different threads.
There is plenty of good reading here.