I've heard they had problems in the actual original vehicle. As for axle...I haven't found any information on that really. Closest I found was with parts train, I don't really understand anything about axles though, anything I know about cars is trial and error, and as I haven't messed with axles yet.. :P This is what parts train says about the replacement for the 6.6L version, which comes out to 402, so I'm just assuming they made an rounded it to 6.6L instead of 6.556 or whatever it comes out to. 8-3/4'', 8-78'' Dia ring gear 30 spline. That's all I've got..if that equates to anything, it's beyond me.
For a little more information on it; It's a 1972 suburban with the "california package", one of the first and only to get this package. The problem with that is it makes any information on it rare. For the most part, I don't believe they put the 400's in 71-72 suburbans. But I Can't find axle information even on the regular suburbans of the era.