Mary,
You have probably found out by now that you certainly CAN have a 1967 230SL. Technically speaking, there are two ways to look your car's "birth" date; either as MODEL year or PRODUCTION year. In the US, your car is titled by the MODEL year which typically begins in September of the year prior. Lets face it, the average car owner is rarely interested in what date their car is produced, only car nuts with a thirst for knowledge like us ever even inquire about the production year.
So back to your question...230SLs with a 1967 model year designation were produced from September 1966 through January 1967. 250 SLs were produced starting in November 1966 (as 1967 models) through December 1967. Starting with September 1967, they were designated as 1968's.
Hope this has helped!
Kevin Caputo
PS: My 1967 230SL was actually produced in October 1966 so she just celebrated her 44th birthday!