beanyard,
55.5 thru 59 is an easy fit, HO33 is the rear diff. type. 10 bolt cover, not a lot of gear ratio choices though. Also axle splines are course, not good with any major horse power, and the axles are different length. Others have researched all this stuff and there is a good list of donor rear diff. choices out there on this and other forums.
Good Luck
