If you have enough time cash and the contacts you might be able to track down a genuine datsun h145 LSD Centre. As far as I know they were a special order part only available to the japanese race teams in the 60's. I have never seen one in the flesh and only heard of two units in australia. So unless your a purist I would consider something else.

Since the h145 is so narrow nothing is a bolt in option .
So with that in mind just pick what ever axle setup you want and get it cut down to fit.

I have a cut down borg warner from an r 31 skyline sillouhette.
Its the same diff that was in the vl-vt commodores and ea-au falcons plus r30/31 skylines and pintaras just to name s few of the cars that came with a BW
Lsd mini spools and a heap of ratio options available make the BW in my opinion the diff of choice .
Plus depending on which. Car it comes from you get discs or drum brakes, built in hand brakes 28 or 25 spline axles

i was thinking of useing the bw out of my old eb falcon but its so damn big and haevy,will keep the h190 in mind and see what icome up with. thanks for the help guys much appreciated