In my opinion, it was a much easier job to swap the 4-bolt stuff into the 3-bolt 4WS diff. I guess a lot depends on what condition your 4WS lines are in, and how much you want to keep the 4WS. If you just drop the LSD into your 3-bolt diff the 4WS won't work because there isn't anything there to still drive the pump on top. You need to either press the bronze drive gear off the old diff, or just buy one from a dealer. I think it was ~$25 from JNZ Tuning. I did a writeup at one time, but I think it was lost in one of the server crashes. I even gave the part number for the roll pin and new bearing that I recommended you also replace. The actual diff is the same dimensions, so there is no performance or reliability reason to replace it. You just swap in the LSD diff, slide in the new LSD axles, and bolt on the 4-bolt hubs.