Thanks Naj, Thelews and Gnuface, I realised sometime after I posted the message that I hadn't specified the engine. It's an early 230SL with the large diameter oil tube.
(I wondered how long it would take for some one to comment on the length of their dipstick
.
The link that Naj posted is very usefull - thanks Naj.
However I'm still none the wiser regarding overall length and markings. (I'm a bit worried about what Thelews might come back with.)
thanks