I can't exactly help you with the sway bar question, but to my knowledge the 2wd axles are 2 inches short than a 4wd axle, so I'd reuse the original housing if you can an swap the guts.
Sent from my 5.7 powered iPhone
X2. Just swap the guts in the diff as long as they're both the same size. (OR take this opportunity to get a real carrier and ditch the junky G80.)