Bob,
If the distributor you're lookin at is from Bushnell, Fl., it seems to be an '048' from the picture and its not from a 230SL.
You can look at the advance curves of the various distributors in the BBB.
Late 230SLs were fitted with the '051' same as 250s and 280s but earlier ones had the '046' which is a vacuum advance distributor. No good to the later vacuum retard set-up cars with the '051'
just my $0.02
naj
68 280SL