Shower tailgate rubber profile wanted.

Hi all,

Desperate to source details and supplier of the rubber waterproof strip that seals the shower in when tailgate is closed . I have never had one so don't know what to look for. Its a tadpole shape i think to fit in the channel 
Any photos / sizes/ sample or God forbid spare one would be amazing. The AS factory can't remember as its 30 years old now and everyone work then is retired.

Also after the original shower head if the one out there. My O ring inside has perished and is extremely rare to find correct replacement for the on /off function to work.

OK, many thanks.