Dana 60 semifloat strength?

[yossarian19]

I've got a Dana 60 semi float out of, I believe, a '68 C15.
Before I go to the trouble of swapping it into my '57, though, I want to get a sense of the axle weight rating between the two rear ends (55T vs Dana 60 SF)
Wikipedia says "up to 5,500 lbs" for a semi floating '60, but then, there is more than one bearing and more than one application for semi floating dana 60's.
Anyone have an old service manual or some such?

Basically, I have a '57 truck that I want to be able to stack more concrete blocks / pile more gravel into. The plate on the door jam says 5,000 lbs GVWR and it's about 3,900 with me and some gas in it.
The 4.8 & 4L60e are up to the task of hauling more, and I want the power lok that's in the '60, but if it won't haul more weight I might keep looking for a new rear end.