Found my 8.8 complete with discs and 4.10 gears for $100. Look hard and you will easily find what you want.
Consider this kit for spring perches and shock mounts, allows the use of standard grade 8 bolts instead of ubolts, and they are very well made. I used a set to put an 8.8 in my Comanche. http://tntcustoms.com/webV4/ubolteliminators.asp
If you want the best in traction for offroad, lockers are your answer. They allow you to go more places than you ever could before but consequently get you into more trouble
Its a rear axle, it should be centered. The 8.8 is slightly offset, but I ran one and I can tell you that it wasnt enough to matter. I do need to update that thread some, I haven't worked on it in a while