I've performed the 8.8 switch on my XJ.
It was relativity painless. I paid $120 for my 8.8 on eBay complete with an explorer tailshaft. Its LSD with 4.1 ratios but I have 4.56 and an ARB locker ready to install. I run my 3.75 BS rims on them with my bushwackers and am visibly / functionally unable to tell that its thinner than the original diff. Works fantastically.
Basically the process was very simple. I bought a kit from know where 2 jeep:
http://www.knowwhere2jeep.com/know-w...erokee-xj.html
Whilst the kit was good, it wasn't perfect. Things that weren't right were:
Hand brake cables are ZJ ones and only work if you have a pre-update model. You can however modify your XJ ones to work.
Shock mounts are not my favourite. I will modify them once I mount my new shocks.
I haven't yet swapped my proportaining valve but the brakes are tonnes better than the d35 drums so its not high on my priority list.
Because of my current exhaust system under flex I get a little bind of tailshaft contact with my muffler.
Would I do it again? Without a doubt, the thing is a monster... The only issue is the pumpkin is massive so you will lose some clearance compared to your d35.
So for me the diff mounted complete with disks on my car has been around about $500 (without the arb locker). I doubt you'll build a d44 / 8.25 for that price.