I think the rubber damper or mount is 54050. And the top cap is 54320. At least these are what they look like when I got it from the stockist. The total I paid was about $183 for a pair of rubber and top cap, since they said must change is pair..
By the way, please also confirm if your shock absorber needs changing or not. I only got the rubber damper and top cap, but when the mechanic removed the shock absorber, he showed me its leaking. Adding on the absorber is expensive with the workshop. If I known should have gotten the absorber outside...