Engine and Transmission Tech

I have a 2.88 ratio diff from a V12 XJS I believe it was a 1987 car, I have identified it as a DANA unit which according to what I have read is an inferior LSD (to the Salisbury), my question is this; as it is from a low mileage (70000) car should I just replace the seals and or bearings at the same time as fitting a 3.2 or 3.3 crown wheel and pinion?
Selling it and buying another with the correct ratios is a possibility but the above ratios seem in very short supply, and what I buy may need rebuilding any way.
Is it worth replacing the LSD as the DANA seems to have a short life expectancy?
if so what make is a better replacement?
Am I right in thinking that any DANA 44 crown wheel and pinion (between 2.88 and 3.54) will fit and if so which brands have a good reputation for not only strength but low noise?
If I go ahead and replace the diff is it a difficult job to shim the gears or is it best left to someone who knows better?
thanking anyone for any advice
Philip

Philip, there are posts in my 340 thread that answer all of your questions if you can take the time to page through the thread. But basically, the Dana44 uses a variety of limited slip differentials and can be fitted with almost anything on the market. Jaguar generally used the PowerLok which is a very durable unit and competitive cost-wise. I can't tell you how durability compares with the later Jaguar IRS but they are not interchangeable. You can get any gear ratio you desire for your Dana, and gearsets cost a bit over $150. Jaguar set the axle breakaway torque low. Re-stacking the clutch plates will raise that and give more positive action for more miles. Dana and Jag used different sized ring gear bolts and this must be accounted for when changing gear sets. You will have to buy a posi case because the gears you want have a different ring gear offset. Match the case to the gear set. They also used different pinion bearing sets and pinion yokes, these much be matched to the pinion and case. You can run Dana with Jag and Jag with Dana with the right bearings and yoke. All else is perfectly conventional.

Jim