Took my diff out and apart to find 2 large pieces of cog wheel sitting in bottom of diff.
Wondering if you can buy spider gears as it's just one side that's broken but also a big pin is half sheared off or am I better to buy 2nd hand replacement diff?
And if I do is there anything I should do other then pinion seal and output shaft bearings as preventative maintenance

 

Also I could find a 3.2 diff are these same as 4.0 diffs bolt straight in?

 

Internal parts are not available now, except for bearings. All the X300 diffs ( and some XJ40 I believe) will bolt in. Just be aware of the different ratios if you buy a replacement and some have limited slip if you want it.

 

Thanks jagboi but what is difference in ratios does it matter do they fit differently?
also does limited slip fit the same as non lsd

 

Limited slip will fit identically to non limited slip. The ratios are all the same in terms of bolting in a differential, just that if your car has a 2.88 you might not want a 4.09 if that's what you find.

From the top of my head, the available ratios for XJ40/X300 were 2.88, 3.27, 3.54, 3.58, 3.77, and 4.09. All were available as either conventional or limited slip. Not all were available in each market and with every engine/transmission combination, but that's the total range of ratios.