2-7/8” fan original Mustang spacer. Vintage FOMOCO part (shown in photo of end) Mounting holes are just a hair shy of 1-1/4" apart (it may be called 1-1/4"). Hole dia. seems to take a 5/16” bolt, which I believe should be 1/2” longer than the spacer. Removed from my 1966 A code 289 when I went to an electric fan.