i have just purchased a standard 99 Blazer with 111,000KMs and would like to get some feed back on some suspension mods or upgrades. have tweaked the torsion bars to get the front to sit straight but need some attention to the rear.
How do I know if it has LSD's in it

 

To lift the rear you can install lift shackles that replace teh stock shackles for longer ones. Therers a "How-To" on shackles and T-Bar's on here You could you also do an Leaf over axle mod which will give you a ton of lift in the rear.

As for the LSD thing, blazers dont have limited slips, they have what is called the G80 locking differential. It's a fully locking mechanical differential. For more information on that just search around here for G80 and you'll find a ton of information on it

 

thanks for the info, I live in New Zealand and this 4x4 came via Japan and is a RHD model.
I have had experience with putting some more set in the standard main leaf spring ,dont really need the really high lift and suspect the leaf has sageed a little. What octane in the gas do you guys run in your Blazers in the States, we have 91 and 98 available?