There is a Jag LSD for sale in the for sale section.
Link to parts for sale -
http://clubcobra.com/classifieds/sho...p?product=7180
3.54-1 gears are pretty common for Jags. They show up on Ebay from time to time.
If you buy the LSD listed in the ad and get a Jag gear set that you want, then you could find a good mechanic to install everything.
You can also use Dana 44 LSD and gears with some slight mods. The Jag was a Dana 44 made under license, so it is very similar.
John