Here's the first place to look...
http://chevy.oldcarmanualproject.com/shop/1947truck/index.htm

And here's the manual page
http://chevy.oldcarmanualproject.com/shop/1947truck/47ctsm0426.htm

The pinion cage looks like it comes out whole, carrying the pinion and bearings. The whole lot should pull apart but it looks like the bearings are press on. You wont get it apart without taking the whole cage out.

I have this job coming up on my 4100, the bearings are ok but the old leather seals have shat.

Best of luck.

'47 Canadian RHD 1.5 ton truck