Crane are still available.
Retubing really isn't that big of a deal, it's just expensive to buy new Cs and have a shop do the labor...crane makes d44 inner Cs, but they're $$$$....and crawlertech will retube your 44, also $$$.
I saw this when I looked.
"Online purchase of this product is currently disabled."
I haven't seen their diffs in forever either.
Have you ever thought about just keeping the wedges and using extended radius arms on your Xj?