What you want is a Hex socket. Sears and NAPA should have them in stock. If not and you don't want to pay Snap-on $$$ try to find a S-K dealer. Good luck.

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2dieseljohn
1979 300sd (283,000+) Road Trips
1983 240D 4-speed (350,000+) Daily Driver
1967 E-TypeS1 in bits and pieces