Hi Chris,
Not sure if you've look at the following URL but they have a couple of options for 19 spline diffs (DANA 44s) that might be of use. Be careful though, as far as I can undertstand you'll need different (possibly custom) bearings and stuff (crown wheel bolt sizes too if I recall) as I think there are slight differences between the jag and dana specs. Also if you avoid the crown wheel bolt issue by buying dana gears I think the pinion bearing is a different size too but again I've only had a cursory look a couple of months back, others may have more/better info on what bolts in and what doesn't.
http://www.ringpinion.com/PartsList....er+D44&CatID=7