If the set of mounts are all the same size there for a 318 engine, not 340 or 360. The drivers side mount is shorter between the ears on the block. And the difference is about 1/2" which is what are you are finding. The 340,360mounts haven't been available for the past several years, unless somebody is reproducing them. Schumacher was at one time making them and maybe the company that is making some of his mounts has started making the 340, 360 mounts. There around and guys are selling them so just a matter of time to them for sale. Some guys put a spacer to make up the difference in the mount, but myself I want the right mount. The 340 & 360 are the same.