Originally Posted by JimFreeh

Here's what I've learned:

Both W114 and R107 mounts bolt to the subframe using the same bolt pattern.

W114 motor mounts have a female thread in the center that accepts a bolt that is dropped down thru the motor mount arm.

The R107 mount, (at least for the euro 280SL) has a smooth bore, and you install the mounting bolt from the bottom, using a caged nut on top of the motor mount arm.

I imagine this is done for clearance, since there effectively isn't any at the top of the arm....

The subframes are the same with one difference:

The lower access hole in the R107 subframe is not present on the W114 subframe. Oddly, the upper one is present on both.

In my favor, the W114 subframe has a stamping that locates where the hole needs to be drilled. I used a 1" hole saw to make the holes.

The R107 also has these neat sleeves that install into the subframe before the motor mount, and these things consist of a cylinder that fits between the two access holes. Keeps the bolt from getting lost inside the subframe. Pretty cool, eh?

Now I'm ready for reassembly, Woo Hoo!

Oh, another trivia item: The upper ball joints have two possible bolt patterns. You have to grind off the rivets mounting the original ball joint and source some fasteners (3) to install the new ball joint. Make sure you use high strength fasteners! Anyway, there is a big and small pattern, make sure you measure which one you have before ordering! I didn't. Fortunately, I had another set of upper control arms with the correct pattern, only cost me a couple of hours worth of disassembly.

Jim