Yeah, I used a caliper with crappy inch markings so about 5 1/4 or 5 3/16s. I just went to mm and roughed the measurement.

I was going to take pictures but I figured I didn't want to waste time after giving you a heart attack.

In that diagram parts layout I reposted of yours it looks to be smaller at the top.

The backs are definitely smaller on 1 side, I just checked.