W124 rearend housing mounts bolt head size?
 

I'm pulling the rearend out of an '86 (or '87), I forgot which 300E. Last night I got all of the triple square axle flange bolts out after a mild battle (serious buildup of grime).

However, I didn't have a wrench to fit the two bolts (allen-head) holding the back portion of the rearend housing to the subframe.

My best estimate is that they are 12mm allen-head socket bolts, but I would feel better if someone could confirm this fact. I only want to make 1 trip to buy the correct tool, and large metric allen wrenches are not the most common grapes on the vine.

Any help is appreciated.

SteveM.