So... I've been thinking again.
I found an article from Four Wheeler from a while back when they bolted in a 4.0/AX15/Dana 300 into a CJ7. The rear driveshaft ended up being 20.25". If you figure my little CJ5 is 10" shorter in wheelbase than a CJ7, I'm not sure if I'm comfortable with a 10" driveshaft.
Let's talk about the T5. Been doing a bunch of research today about them and it's a real mixed bag of opinions. Looks like the 3rd gear is the week link in the whole package but I'm seeing more horror stories from people trying to go way above and beyond what you should with a T5 anyhow. My current T14 three speed is also in that same boat of being classified as a lighter duty transmission. I don't see myself using my Jeep as a real rock crawler. Rather I find myself wanting to go out into the mountains exploring back roads. The gear ratios of the T5 are 4.03, 2.37, 1.50, 1.0, and .86 while the T14 has a 3.10, 1.61, and 1.0. A lower first gear would be nice and obviously I'm still after an overdrive. If you look at the AX15, it's got 3.83, 2.33, 1.44, 1.0, and .79. Comparing a TJ on 33s and 4.10s or 4.56s with an AX15 would be real comparable to my little CJ on 33s and 4.27s with a potential T5 in it.
Not sure if I've got a question in there... more so just thinking out loud. Anyhow, tell me more about your CJ5 plans.