What are the differences between the x300 upper control arm and the XJR/8 upper control arm? Are there any?

Powerflex does not list options available for the front upper control arm bushing for the x300 yet the XJR/8 has them listed...

Powerflex X300
PowerflexUSA - XJ6 - X300 - X308 (94 - 02)

Powerflex XJR/8
http://powerflexusa.com/jaguardaimlerxj8-r-sport1997-2003frontupperwishboneBushing-pff27-302.aspx?variation=8696

Is it safe to say the XJR bushings will fit our customer's 97 XJ6?

 

Dunno (but am curious to hear too), but another option are Andy's (XJREngineer) bronze upper bushings. I suspect a noticeably harsher ride, but probably the ultimate in performance and durability for this given part.

A search should find some threads/posts on them. You have to send the wishbone to him in the UK to fit the bushings.

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Poly is a jump for me if I did this. I have the URO bushings waiting for install but if I can solidify the front end without making my teeth chatter that would be greaaaaaaat

 

I see your dilemma. The OE part number is the same for X300 and X308 upper control arm bushings. May be worth a call to those people for specific application.