Dave, I would wait till you can measure your own. Pay attention to where the original screws are so you can be sure the flange on the replacement dome, will cover these holes.
Don't know about the other manufacturers listed here, but the Ezee tops I linked to, and purchased, the flange is only 1" wide. The original skylight flange was wider than that ( 1.5" or a bit more). I remember when I got mine thinking I should have ordered it 1/2" longer in each measurement, because the flange just covered the existing holes on one end.
I drilled all new screw holes.
Ben & Sharon
2008 43' Holiday Rambler Scepter PDQ