Couple reasons that it isn't a common swap...
1- Toy front axles have the diff on the wrong side to fit in a Cherokee. You can change that, but it isn't worth the work or money.
2- 4x4 Toy's have 6-lug, versus the Cherokee's 5-lug. Unless you swap both axles, you have mismatch lug patterns, and if you do swap both, you need new wheels.
3- Toy axles are significantly narrower that a Cherokee's stock axles. Spacers are fine I guess, but they wreak havoc with your steering when they get any wider than maybe 1.5".
4-As far as the GM 12 bolt... They are just GM's version of the Dana 35. It is just a bigger, heavier pile of junk than the Dana 35.
Not worth the time or effort.
Putting a Toy rear axle into your Jeep may be an OK deal, but just the rear. 2wd Toy rear axles are neat because they have the same lug pattern (5 on 4.5") as your Cherokee (They do have metric studs unlike your Cherokee, but at least you can use your existing wheels...) Find yourself a 2wd truck with the 8" diff, weld on your spring perches and shock mounts, and use spacers to achieve the desired width. You'll have to source a drive line flange/adapter to make the Toy flange pattern mate up to your drive shaft though. Not a real tough swap. There are a couple around the valley that I've heard of and they work out sweet. Maybe some of the people that have them will chime in and tell you what they think.
Hope this is what you were looking for.