Hi all knowing community.
I am trying to source a rear differential for my XJR, but I'm not having any success.
Can an XKR differential be used if I swap the pinion over from the xjr differential?
Any help very much appreciated.

 

It is not advisable at all to swap pinion gears between two (identical) diffs. The pinion shaft/gear and the crown gear are a matched pair so changing the pinion gear only would most probably mean a "singing" differential.

However, in the case of XJR and XKR diffs, they seem to be identical in all respects (including their ratios) except for their input flanges. You can, most probably, just swap the flanges, the 4-hole one with the three-fingered one. I am only talking based on comparison between the XJR and XKR diff parts diagrams. Others who have had actual experience with swapping these diffs will provide better advice.

 

Thanks for the info. Sorry, yes I meant the flange. Not the pinion gear.
so there might be a way. Good.
I'll wait a while to see if anyone else posts any experience before jumping into this.
​​​​​​

 

I have successfully done the XJ into the XKR diff swap.

Customer had 4.0 XKR but wanted the diff swap to 3.27:1.

Found a MEXICO 3.27:1 XK8 diff and had it delivered.
I installed it while his TCM was sent out for reprogramming for the different ratio.

Months later the diff was making a horrible clacking noise. Found a broken tooth on the pinion gear. (too much hotrod?)

Found a 3.2 liter XJ8 diff in the UK and had it shipped to US.(yes the ratio is 3.27:1)

I cut the pinion shaft JURID flange extension and swapped to the 'U'joint XK flange.
(be careful to set preload correctly)

I don't know how you can add an extension to fit the JURID for centering to go the OTHER WAY?

Will it work without the extending metal shaft into the coupler?

 

have a shop mod the XK driveshaft flange onto the rear piece of the 308 shaft?

308 diffs are very easy to find, where are you located?