Whiteline bars used to be the way to go if you wanted to keep 4WS (or just in general as they were quality parts) but they're NLA. If you look through the ForSale section you'll see a thread for the last few parts from this now_extinct product line.
Most 1G bars will interfere with the 4WS pump located on the top of the differential (or maybe it's the lines that hit, I don't remember). You can use a 1G rear anti-sway bar IF you remove the 4WS pump or switch to a 4-bolt rear diff. The only exception that I know of is the RM bar which WILL fit even if you have 4WS despite being advertised for DSMs.
click . I installed one in my car back when I had 4WS and it's worked very well for me.