Spacers don't ride the greatest and don't do anything for the truck off road wise if that's what you're wanting it for. You're limited by the amount of travel your springs have, so you wan't gain any articulation and the droop will be limited by the the down travel of the shocks. So the only advantage you would get is tire height clearance, which it sounds like you're not wanting to go bigger on tires at this time. The only advantage you'd get is approach angles, but if you're not wheeling on the rocks, then that means nothing for you.
Body lifts suck in general. You'll hate yourself, plus a quality suspension kit is about the same cost and honestly easier to install on these solid axle trucks.
On my 99 and my buddy's 98 Rams we put 3/4 ton springs under the trucks and gained about 2" or so. Throw an add-a-leaf in the back and some cheap hydro shocks on, you'll be set.
