I am looking at SL's and found out that Steve is correct. You need to see if it has a double timing chain. Some of the 81 - 83 models had them retrofitted before they became standard in 84 (maybe thats why its in the garage?). If not, I read where the single chains need replacement each 40k miles.
Watch out for Deezel. He just might avoid any problem by dropping a diesel engine in it, really grossing out everybody following behind him! jk
'75 240D 300000 miles