Ok pigdog, the penny is dropping.

My short axle becomes the new LONG axle
My long axle gets cut and resplined into my new SHORT axle

My new diff is going to be 10mm wider each side than the standard 1200 ute diff, which should make mine the same width as yours.

I am doing this so I can fit larger tyres and the front and rear track will also be the same. Its out cause of the silvia front disc brake conversion.

Its cool, things are slowley falling into place. Just have so sort out the hand brake once the new diffs in, modify the brake lines to fit and sort out a custom tail shaft