Stupid question of the day! 360 motor mounts

Hi, I seem to be having a problem getting the proper driver side motor mount for my 360. The big 4 parts vendors in my area ( autozone, oreilly's, advance, and napa) all show the same anchor 2326 mount for both the 318 and 360. The problem is the mount is a half inch too wide wear it mounts to the 360 block. I tried it on a 318 and it fits great.
The anchor brand mount is 2.75 wide and the oem 3817235 mount is 2.25 wide. I just held it up to another 360 and its the same deal. My block is from a 1979 new yorker that donated itself for the cause.
So what am I missing? I know the mounting ears on the 360 and 318 are different widths. Are all the aplication guides at the part stores wrong? I have went through several different models and years and they all come up as the wider 2326 mount.