The XR4x4 V6 uses a 7" 3.62 and the DOHC XR4x4 uses a 7" 3.92 Viscous LSD's. The XR4i V6 uses a 7" 3.62 non LSD diff however uses the push in style driveshafts so isnt a straight swap. Ideally the easiest way to convert a XR4i to LSD with the same final drive is to use a whole rear beam from a mk1 XR4x4, alternatively a mk1 Cossie as the final drive is near dammit the same. and you get rear disc's as a bonus