First, make sure it's the Eaton axle and not a later-style GM corporate axle. The dome-shaped rear cover and drop-out differential should take care of that. To check the ratio they can either pull the rear cover and check the numbers stamped on the edge of the ring gear or simply count driveshaft v. axle rotation. I think (but I'm not sure) that my ring gear is stamped "41 10."
If it is a 4.10 and you get the whole axle, I'd love to know if the later finned brake drums are the same diameter and depth as the smooth AD drums. I stupidly didn't measure them when I pulled my differential and haven't had my hands on an H052 axle since.
