'06/'07 WRX were 3.7 and 1:1 front and centers? I thought the only 3.7 from the post GL era were the early fwd manuals. Sweet. Good to know.
Midnight in a Perfect World on Amazon or order anywhere. The first book in a quartet chronicling the rise of a man from angry criminal to philanthropist. Midnight... is a distopic noirish novel featuring 'Duchess', a modified 1990 Subaru Legacy wagon.
Swapping the diff isn't that difficult if you can check the backlash. Pull the retainers from the sides, remove rear diff cover, remove stub shafts and then the ring gear off the Clutch LSD. Then do the same for your stock diff (so you can retain the ratios you need). And bolt it all back together, but with the stock ring gear bolted to the Clutch diff in the stock diff housing.
I'd love to get my hands on one of those, but I think I'll continue hunting junkyards before I drop the money. Good find!