[bagged91]

There are a few drawbacks to "mono leafing" your truck(or any truck for that matter)...

You will most likely get some wheel hop.
You will most likely get some spring wrap.
You will most definitely have issues with your pinion angle
You will be limiting your ability to drop super low(if that matters to you.)
Your ride quality will not be that nice.

I would recommend saving your money and 4 linking the truck. You will be much happier in the long run.

Now, to answer your question. Most people will mount the bags directly over the axle tube. You can figure on getting approx 6-8" of drop/lift with this setup. With my 91' GMC, I am getting 13-14" of lift using a cantilevered, triangulated 4 link(bags are mounted on the link bars). The front is easy. Just swap the coil for the bag. Suicide doors is selling the front brackets for like $59.95.