Everything you need is for sale right here. There is no difference between the 350z pumpkin and the 370z pumpkin (except for a slight size difference in the rear diff mount but that has nothing to do with installing gears or an lsd).
If you go on z1 motorsports website, the install kit is the exact same for 370 and 350.
370z:
http://www.z1motorsports.com/g37_370...oducts_id=4529
350z:
http://www.z1motorsports.com/350_g35...oducts_id=4523
They have two different pages because the 4.08 gears give a lesser increase in acceleration on the 370z because stock fd gearing is 3.7 as opposed to the 3.5 from a 350z.
And no I did not get this kit through z1 but its the same exact install kit.