I have a set of engine mounts in a box up inside my ceiling I could pull out if no one gets back to you but it will be a real pain in the a$$ for me to get to them i reckon art least 45 mins to find them and measure and then put it all away again.If no one replies let me know and I will do it as a last resort.I have found plenty on the internet stating the holes are 7" apart (177.8mm) but I don't know what the hole diameter is.