Well for a start my current setup I have the V6 commodore motor and a supra 5speed and the hilux diff with a 3.54 ratio in it. At 100kph I am doing 2800rpm yet I know that my old mans commodore does 180kph @3100rpm.
So my point of it all is that as far as I am aware 3.54 is the best hwy diff you can get. If they make a flat 3 or there abouts I would get it but I haven't found one yet.
So getting a nine inch I can go a get a flat 3 for hwy use and daily driving and when I get the urge to race at the strip I'll have the other ratio to bung in ( either 3.9's or 4.11's etc)
So if you know of a ratio 3.54 or under let me know.