Hi I’m trying to buy a set of valve stem seals for my Mercedes w114 280ce 1973 engine number 11098112006291but it seems there are two sizes for the exhaust valve. Some websites say 9mm diameter valve stem others say 11mm diameter. I think all the intake valve are all 9mm.

Can someone please shed some light on this even better send a link to the stem seals I need.
Thanks.