Is it possible to bolt the XJ40 valve cover on an X300? Forget the coils for a moment, will it fit on the head?
S.

 

The 3.6 and early 4.0 won't work even if they fit. There is no oil cap on the cover to add oil to the engine.
The 4.0 XJ sedan covers from VIN 667829 have an 'oil cap' so they would be only ones to consider.

I never tried to fit one when I had engines apart when I worked at the dealer. I now wished I had tried it.

bob

 

The bolt pattern is different. Also, the gasket part number is different which would lead me to believe the overall shape around the perimeter is different as well.