I got some used Advanced Design shocks and struts a while ago and I'm finally getting around to putting them on my second-gen RX-7.

The problem is the bottom shock mount in the rear, where the shock mounts to the hub.

I got new mount-bolt things from Ground Control that are supposed to replace the part that bolts into the hub and sticks out for the shock to bolt onto. It's a piece that's a bolt on one side of it, and a post on the other side that the shock goes onto.

The problem is that the part that I took out has bigger threads than the part that Ground Control sent me. Ground Control claims that the part they sent me is the correct part for the car. This doesn't seem right to me, as the part I took out seems to be the factory piece with no modifications.

Has anyone else changed out this part? Are there two different hubs or something with different size mounting bolts that go into them?

Ground Control says that there are no other, alternate parts for that car. How can this be?

Any help would be appreciated. Thanks in advance!