Stock radio/mounting bracket screw hole measurements?

[BaconatedGrapefruit]

I'm doing an install on a 95 Avalon and I won't have access to the car until I go to put everything in. Since I'm fabricating one of the single din units myself, I need to know the exact spacing of the screw holes on the side of the head unit used to mount the stereo to the bracket (to drill holes beforehand). I measured my Camry's stereo, and the hole spacings seemed very odd: one was about 1 1/16" from the front and 9/16" from the top of the unit, and the others were centered 1" from the top/bottom, and 1 7/8"and 3 7/16" from the front. These dimensions seem unusual, and they weren't even exact (often almost 1/32" off). Is there a standard hole spacing for all head units? I'm having no luck finding it with google. Thanks!