Hangers = front of leaf spings
Shackles = rear of leaf springs
Hangers = grinding out factory rivets.
Shackles = swap out with 2 bolts per side.

 

I'll add to this
Hangers= Major pain in the ***
Shackles= Extremely easy. 1 hour job.
Leaf springs= very easy. noticeable handling difference.

I'm running 4" hotchkis leafs in the rear and it doesn't ride very smooth but handling is night and day. I just need to get the hotchkis rear sway bar and hotchkis coils and i"ll be happy

 

we did some 2 inch shacles on my budys 00 silvy. its looks better and didnt take very long at all.

 

only took me about 2 hours to do my hangers

 

Hangers are a little of a pain, but I think it's just more time consuming than anything.
it's very easy to do when you remove the bed. The bed is easily removed (8 bed bolts, fuel filler neck, and unplug tail light wiring). You just need to remove tires and as long as you and a buddy are strong, you can take it off with 2 people. A overhead lift or hoist will take it off without any help.
If you have a good neumatic air chisel, you will be able to pop each rivet in 10-15secs.
Just to add, it may help if the rear shocks are unbolted from the axle.
When reinstalling new hangers, be sure to bolt the leaf spring to the hanger before bolting the hangers to the frame!! Yeah.....Just ask me how I would remember this particular step so well!
Tighten all bolts down firmly to the frame. I'm not too sure how tight to get the leaf spring eye bolts, but they can be pretty tight.

Shackles will require removal of your tow reciever hitch. Don't forget to unplug the trailer wiring harness.
Decompress suspension by lifting truck up by the frame and support it by jack stands. Place a floor jack under the middle diff.
You can then unbolt the shackle bolts. Be carefull as there could be a little tension still on the leaf springs.
Replace the shackles with the new ones and be sure to reinstall them the same direction as the old ones were.
Do NOT tighten the bolts. Just barely snug them.
Next unbolt your bump stops from the frame. Then remove the bump stop off of the bracket it is attached to. Then trim 2 nubs off of the bump stop. Bolt the bump stop directly to the frame without the bracket. The frame has holes in it to bolt it right up without any issues.
Now, lower the truck down and compress the suspension by jumping up and down on the bumper.
Then snug the shackle bolts down. Do not over tighten them or they will squeak!
Aftermarket shocks are optional with just a shackle drop, but if you do shackles and hangers, you will need shorter shocks.
Bolt your receiver hitch back up. Your done!
Go for a test drive and PRAY you don't have driveline vibrations!!!

Jim