Soooo picture time!
I have no idea if the measurements will help anyone with finding a replacement but.
Mast Width - 2 3/8"
Mount width - 3 1/4"
Mount length - 3 1/2"
Hole and slot width - 1/2" and 3/8"
Distance from bottom to bottom of hole - 1 3/8"
Distance from bottom to bottom of slot - 2"
Bolt holes - 1/4"
Bolt hole distance width wise - 1"
Bolt hole distance length wise - 1 5/8"
As for the connector I did some csi work today and the person that was with me said he disconnected that stay after the mast fell so I checked the connector and it was fine.
To make sure it was fine I loaded about 250 lbs of weight hanging from it to see if it was cracked or something that I could not see.
I think what happened was the stays were a bit too loose and the mast had some side to side give and ended up snapping this mount when the boom switched from a tack, does that sound plausible? It is the only thing that is broken.