On GM rear axles there is a relationship between the number of bolts holding the cover on and the strength of the axle.
But the number of bolts holding the cover on is not what gives it more strength.
The strength comes from the increased size of the ring gear and the related parts. More bolts are used to hold the ring gear in place which probably does contribute to the strength. You commonly hear Ford axles called eight-inch or nine-inch and that measure relates to the size of the ring gear.
On the GM 10-bolt axles there are several size dimensions that I've seen, so its a little more complicated to know exactly what you have. A 12-bolt is generally stronger than a 10-bolt and the 14-bolt is stronger yet.
