Ooh! I just saw the word "case"....darn. Anyone know where I can find one please?

You need something like this, but with the vLSD if your car has that or you can swap out for a quaife. But this is an example of the whole 'pumpkin'. Just check ebay for one that fits what you need.

03 08 350Z 350 Z Coupe Open 3 5 Differential Diff Z33 | eBay

I don't think mine came with VSLD. Anyways to verify this (I bought mine used)? Will any Quaife fit (presuming made for 370z)? Any particular requirements?

well if you want to go 4.08 don't use the automatic diff and the 350 and 370 diffs are the same p/n's. I would say figure out whether you have a vlsd or not and buy the manual diff for the stubs that you have, because if you do use a 350z case you will need to reuse your stubs because the abs tooth wheels are different.

so here is a scenario for you:

If you're buying a 350z manual pumpkin, and your 370 pumpkin doesn't have the vlsd-->buy a manual base quafie unit, 4.08 gears and install parts, and reuse your 370z side flanges

If your buying a 350z manual pumpkin, and your 370 pumpkin does have the vlsd--> buy a manual quaife unit for the vlsd(or the base quaife and the extra base side flange), 4.08 gears and install parts, and reuse your 370z side flanges(or replace the long one with the spare short one if buying the base model quaife)

If your buying a 370z manual pumpkin, figure out what factory diff it has and buy the appropriate quaife for that diff, 4.08 gears and install parts, and bolt it on.

If you buy a diff from a g35 or g37 sedan (possibly x coupe also) you will need to swap the front driveshaft flanges on the diffs when you install the gears because those cars have a 3 bolt flange instead of the 4 bolt.