How do I convert my leafs to coils?

[Anthony Fremont]

I have a 66 GMC 1/2 ton w/leaf springs. How hard is it going to be to convert it to coil suspension? I've searched around and haven't been able to find a good description of what needs to be done.

1) Are all the frame holes already present? Do I need to weld or drill?
2) What do I need besides trailing arms and a trackbar?
3) Can I use my existing rear-end? Do I need to weld spring mounts or anything else on it?

I want to lower my truck and I'd rather have the ride of coil springs anyway. I can get a rearend from an IROC with disc brakes for $200 locally. Anyone have any idea how hard it would be to put that in?