If you haven't seen it yet, 4X4 Garage magazine for this winter is packed with articles for us YJ guys as well as covering a 231 t-case build up and a intake shootout on a TJ... Definitely worth picking up a copy.. some of the key write ups cover
1...2.5 to 4.0 engine swap
2...various methods to eliminate the vacuum disconnect on the D30
3...spring over axle conversion including a seperate write up on pros and cons of it.
4...a complete jeep front and rear axle application chart including what they are, what they came in, all the specs on them and the pros and cons of each.