Hello,
I am looking at replacing my rear shocks and the spring insulators.
Do I need a spring compressor to do this job?

 

Someone made a good Youtube video on X300 model mater

Motorcarman ( Bob ) has a shortcut involving the lower plate

The rear shocks may have a lower attach point solid bushing that should be considered

 

Someone made a good Youtube video on the matter

Motorcarman ( Bob ) has a shortcut involving the lower plate called the
Suspension subframe as item # 13

Genuine Frame Carrier-rear For Jaguar Xj 1995 - 1997 (from 720125 To 812255) Classic | Jaguar Land Rover Classic Parts





The rear shocks may have a lower attach point solid bushing that should be considered

See item # 17

Genuine Damper And Spring Fittings-rear For Jaguar Xj 1995 - 1997 (from 720125 To 812255) Classic | Jaguar Land Rover Classic Parts

and

What that attaches to can't recall

 

The short answer is NO. But there are several different ways to approach the job, mostly documented in here. Some have used compressors.

I found it relatively easy to undo the body mount in front of the wheel, loosen the rear center of the subframe, take the brake caliper off and let the axle/A-arm drop low enough to let off the pressure on the lower shock bolt and the spring. Then you can muscle out the spring/shock assembly. You can do one side at a time this way.

 

I never could find the video that appeared as a post

I have not done the job

Autozone and other auto parts stores have tool kits including 2 types of professional robust spring compressors to use for free if you go that route

I used the spring compressors kit on some other unworthy car other than the Jaguar

 

here is a video of one method