They are D44's; probably 3.07 or 3.54 ratios. They are good for moderate wheeling up to about 35" tires with a gentle gas pedal.
They use 1-piece axles.
I've got a quadratrac; I'm very happy with its versatility (4Lo full-time is handy for tight turns on rocks; just turn the e-drive switch and you've got easier steering again), though I'd go to a gear-driven case if I went with an engine that puts out over 500ft/lbs.
* '78 Cherokee 4-door "S"
* '88 Grand Wagoneer
* '84 XJ Cherokee 2-door FOR SALE- $600
All that and more on the page below:
<a href="http://home.off-road.com/~wagoneer/" target="_blank">http://home.off-road.com/~wagoneer/</a>