Speedometer gear wear

The "off-center" wear could be attributed to the use of a different sized speedometer gears during the lifetime of the trans. You'll notice on the gear housings that they need to be "clocked" according to the # of teeth for proper clearance. i.e.: 26-31, 32-38, 39-45.

I never noticed or paid attention to the wear spots because I always ran my race transmissions with the hole plugged. It may be normal. There is a load pushing on the pinion.