[thecatseye66]

Originally Posted by 6600DURAMAX

Curious to what are the major benefits are ?? And do you just put the same number of shims behind the a-arms?? Wouldn't it be easier to just rebuild the old unit??

Disc Brakes!!!
This gets those DB spindles under these old trucks without having to do the mix and match thing with the A-arms and ball joints and steering linkages. One big swap makes it easier to find parts in the future because you know that the whole thing is off of a certain year. If you try and piece it together you can have a ton of headaches including a loss of turning radius.
Shims: You'll need to get it realigned because the new assembly will have it's own characteristics...the number of shims will be determined at the time of the alignment...