Any differences between 2WD and 4WD cast iron bell housings?
 

I noticed that the 2wd housings have the boss for crossmember mount, do factory 4wd use the same housing or their own specific version with no mount boss?

Re: Any differences between 2WD and 4WD cast iron bell housings?
 

Yes, 4wd bell housings don't have the mounts. You can use a 2wd bell housing on a 4wd, though.

Re: Any differences between 2WD and 4WD cast iron bell housings?
 

I think the center hole varies from 4 speed to 3 speed.