I ordered the same one from IE. Are you saying the 325 coupler is larger than the 318? So the new coupler from IE isn't going to work?
Unfortunately, I didn't take a photo of the rubber coupler I took out of the 325, but, I believe it was larger. The diagrams RealOEM has for this component are misleading. It shows that both the 318 and 325 use the same coupler assembly when clearly this is not the case with my cars.
On a related note; I was experiencing sloppiness in the steering of my 318 and at first thought the coupler was the culprit. After some research, I read about tightening the large nut on the steering column shaft. The nut felt tight at first but, with a large enough crescent wrench and extra effort, I was able to turn the nut a few times. If you haven't done this yet, now's the time before you take shit apart.
The nut is located on the steering shaft just before it disappears into the foot well. You'll have to remove the knee bolster in order to get access to it. Just grab the steering shaft and shake it; if it rattles, the nut is not tight enough. Good luck.
Nut is just above item #1