LockRight locker info here:
http://www.powertrax.com/
Pricing here:
http://www.lockright.com click Application
The Power Brute LSD is still a research project in progress. If you look at Lockright you will see both the LUV and the 84-87 trooper use the same part for the locker, have the same number of splines on the axle, etc. If you go to the
Isuzu Trooper FAQ, they point out that PG Power Brute LSD part number TL14-4 will work in 85-87 trooper rear axles. I searched that part up and found this info:
http://www.reiderracing.com/pgbrute.htm
So, while there is no guarantee that the LSD will work with the LUV, the 84-87 Trooper appears to use the same axle, and so the same LSD *should* fit in the LUV that fits in the Trooper.
Confused yet? I am I'm sure. I have not found anything as far as upgrades to the front diff, but just getting either a locker or an LSD in the rear will net you 50% more traction. The only time I have ever had to get pulled out of being stuck was because I high centered the front end with one rear tire stuffed in the fender and the other barely touching the ground. This was in my 2WD, but an LSD or a locker would have had me out of there in seconds instead of hours.