Nissan Patrol axles will be strongest, then Toyota Landcruiser 80 series from discussions on other forums and conversations I've had with Cleggy about the patrol axles on his TJ. Patrol axles come with 4.68 (ish) gears in, locker in rear and have the front diff on the correct side for older Jeeps. The rear is huge and they must be at least as strong as D60s. Toyota Landcruiser will be stronger than D44s and they are not Dana based in any way from what I've seen, they have drop-out 3rd members and the rear ring gear is bigger than a Dana 60 from what Mik was telling me when he was selling his old, big XJ.
RWD newer transits use a D60 based axle I believe.
