an r160 with a swapped ring & pinion will work. You just need the 3.9 and the r160 will work great.
on a seperate subject, the older legacy's had a 3.90 ring & pinion setup already in an r160. If you need any further info on this, just pm me. I have done the 6spd swap with 3.90 r160 ring & pinion setup before I went to my r180 currently, which holds the first "working" set of DSS axles...
