You may have been sold the wrong prechamber.
The proper number depends on your engine number.

If the last last 8 digits of you engine number are earlier than :
10 121328 or 12 035839 the part number is 615 010 01 52

If the last 8 digits are later than :
10 121329 or 12 035840 the part number is 616 010 01 52

Look at your invioce and see what you got. Then check your engine number.

__________________
Rusty Cullens
BuyMBparts, Inc.
1-800-741-5252