http://www.deere.com/en_US/govsales/...inks/42_43.pdf
This link will provide you with info regarding 400X and 400CX loaders. This same link was used in an earlier discussion regarding 300 series loaders (and 419 loaders).
Nonetheless, I believe if you root around the site and review the *.pdf files that are available, you should find info regarding the 8B backhoe.
I don't have the specs (need to track down my owner's manual) for the 8A but I'll post them later (gotta get to work...).
We can compare specs at that time--- but, I would venture a guess and state that aside from a small refinement of mounting brackets --- the hoes are virtually the same in capacities.
AKfish