this is a tough question becuase there is no single cause for "death wobble". you're going to have to give us lots more information. for starters, whats your caster set at? have you checked all your steering components to make sure they are tight? no slop or worn out TREs? picts of your setup might help as well.

Jeeps typically have death wobble due to track bar alignment issues after lifting. this is a function of their 4-link suspension and totally unrelated to a leaf sprung Isuzu SAS setup (I'm assuming you choose a leaf setup for your SAS)... again, why the words "death wobble" are so vague.

-Rob