18Diameter x 1.250 thick
Backside has a face 1.875 wide then it drops 1 to a 14.125 wide surface
There is a i OD. tube welded in the center sticking out 2 on the outside face.
There12 1/4 bolt holes in a 17 circle
The bolt on Ring is 18 OD x 13.75 ID has matching bolt holes the back side has an 1.5 face with a 0.180 o ring cut in it .it drops .250 for a 0.625 wide surface with another 0.180 O ring cut.