Jim,
I just returned from the hangar. Here are the photos and measurements. BTW, the round thing under the top wing is the mirror used by the instructor to view the horror on the face of the student. The fuel guage is a clear tube hanging vertically. You can see them both in the photos. The face of the mirror is 4 3/4" diameter with a metal ring around it that has a a 5 1/4" O/D. the ring is about 3/32" thick. The morror housing is cone/bullet shaped like an old 30/40's headlight bucket. It is 5 1/2" deep from front to back. The fuel guage is a clear tube 6 1/2" in length and about 3/4" diameter. It goes into a plug about 1" from top to bottom. The throttle knob is about 1 1/4" in diameter. The ridge is actually a removable curved square piece of channel that is 1" square on top of the wing that is bolted to two square mounts. This appears to be a support for the fuel tank that is in the center of the upper wing. I do hope all this helps out.

Best Regards,
Flak