I have the OEM Lamco boost gauge and was thinking about replacing it. The out to out dimension is +/- 1 11/16" on the bezel (inside the mount). It's a mechanical gauge, so I fairly sure that eliminates Autometer, since the smallest they have is 2 1/8". I did the searches and have the same question you do. Hopefully, highspeed forum rangers will help us out!? Hello...anybody out there?