Apologies for my lack of clarity - it was the following that I was referring to and I was just suggesting to the OP that it might be worth checking it is fitted:
ChrisC
Member
2.3k
Posted November 30, 2021
I have it in writing from CC, it was added for clearance between the chassis and the gearbox. If you think that statement through, that means clearance is marginal without it, something that's been known for some time. Given the price and how easy it is to fit, for me it's a no brainier, on any pre 2021 5 speed Mazda boxed car, especially if your working on the car in that area.
That said, the reason it dramatically reduced my cars noise wasn't because of clearance, it was because it altered the prop working angle slightly, which combined with a faulty front UJ meant a reduction in noise and vibration. Ultimately my car was only fixed of vibration and unexplainable noises with a prop replacement.
As Chris implies above - clearance between the chassis and gearbox is marginal without the spacer.