well as you will see in the other post (we posted at the same time), you can get the discs on a 145 anyway, but, if your still intrested

im not 100% sure on the 120y but from what ive seen,

the 165 from a ute will be the right width,

if you already have a borg warner the diff locaters on the leafs are diffrent,

if the 120y and 1200 tailshaft are the same length, then a ute tailshaft will work, if not you need to get one made

that said the 165 is a good upgrade

no changes will be required to brake lines etc