I have looked at the spydertrax as well and can't remember why I didn't look into them more, I want to say the cost and I am looking for a "Bolt On" axle even though I know that I may have to massage everything to Bolt it on. I love the information though. I have to weigh a ton of things before I pull the trigger on the purchase.
I am toying with building a full on truggy and it will have Spidertrax axles under it. As for "bolt on", well I think you have to consider your tubes are thicker and therefore things don't line up exactly as they did with a 44. There usually are things that have to be adjusted for.
One last thought. You put the 5.3L in because the 3.8 was a dog, right? Now your Jeep performs like it should, right? Ok, D60 up front, D60 or D80 in the rear and you just added what, 500 lbs to your rig? Maybe more. What will that do to performance? Handling? Braking? If your wheeling style allows for running D44s, why not save the money, save the weight and run them? A PR
or TF 44 front is a nice set up. You could also consider a D44 Rubi take out axle. Add an Artec truss, Cs, RCVs, your Reid knuckles. That would be one tough axle and a lot less coin, weight and hassle than even a PR44 or TF 44. (Don't forget the tubes are bigger on those, so "bolt in" is somewhat a misnomer.)
Getting back to Spidertrax, I am not sure, but I would venture a guess that they will weigh less than the D60s. Possibly something to consider if weight is a factor. If you don't mind dragging another 500 lbs around, then D60/D80 is bullet proof.