The Porsche factory race department recognized the need for precise shifting under the rigours of competition. Under severe cornering loads the engine and transmission would move around, causing difficult and sometimes missed shifts. An added benefit was additional rigidity of the chassis.
We have replicated the mounts as used on the 73-75 RSR using aluminum alloy. These will fit as engine mount replacements for 1965-1989 911 models, and the transmission mount replacement on 1972-1986 models. Note that the extra rigidity of these mounts , when used to replace the 915 transmission mounts, cause a lot of additional noise to be transmitted through the chassis. Engine mount installs vary from car to car, but there is additional noise. Just not as much as when used on the transmission!