Technical Brake caliper movement

Yes, the inner mounting hole. And it is the only hole which differs from the other caliper which is not moving.

I could not measure the o-ring groove diameter but seeing an oversized hole on each side of the groove tells me the groove diameter is likely oversized as well (and based on the movement).

 

Ain't that something?

As previously mentioned, I would also look for an AC-DELCO pin and hardware set.

They said they are sending an exchange caliper?

 

They said there were but I have not heard anything for 2 days.