Good point Brian. Regardless the weak point on a all-thread and partial thread still will be the threads as they are exposed at the diff bolt hole entry point.
Another alternative is: Since the bolt hole on the Diff is a through and through a nut and washer can be placed on the back side.
Chase the hole to allow a 14mm bolt to be a slip fit.
Sold here in 14x1.5 and 14X2.0 (the 220mm is 8.6" long for example, plenty long enough)
https://belmetric.com/m14x1-5-fine-d...H14X1.5X220YLW
Have to measure what you need once the diff is remounted.