As posted above, time to break out the dial indicator. I have used sections of steel strip bent cold. Clamp or bold the steel to a feature on the axle or housing and bend to get the indicator where needed. A hole and 1/4" bolt to hold the indicator. At least you can check the axle ends that way.

Also it sounds like you trust the machine shop. Still would not hurt to get the drums themselves checked or maybe find a known good drum to mount and check.