Boosted Falcon

What 9" diff will bolt straight onto my ute it's an XR8 AU Series II ute (manual)

i don't think any do. you take your diff out, have your axle tube's put into a 9" 28spline centre. not that expensive for a diff shop to do, around $500 i think. it's expensive if you want bigger axle's or tru-track centre etc. driveline section may of been the go for this.