You have the older style tumbler. You will need to replace it with another old style tumbler (which are still avaliable from the dealer) or replace the entire steering lock assembly. Here is a thread where I was asking about removing the old style tumbler: http://www.peachparts.com/shopforum/showthread.php?t=180934&highlight=Tumbler

__________________
1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine