Originally Posted by Diseasel300

961 is out of a 300SDL. Block is strong on them. Check the head casting to determine how good your engine is. #14 head is weak, but can be reliable if the engine is maintained and never allowed to overheat. #17 or later is desirable for long term durability. I wouldn't get too hung up on the head issue, I'm running the original #14 on mine, and several others here still have their original #14 with way more miles than I do. More info on how to tell here: 1986 w124 300d cylinder head cast number