What is the best and most cost effective way to produce a 3" lift in my 78 Ford F-250? 3" shackle? 3" lift block??? or otherwise?

 

new front coils, something like this http://broncograveyard.com/bronco/i-..._lift_pair.htm

blocks
http://broncograveyard.com/bronco/i-...th_u-bolts.htm

if dont have front leaf springs you can use thoes coils in the front, just remember never put blocks in the front. When i lifted my f100, i got the new coils for the front, blocks for the back and a dropped pitman arm.