[VAC] Ball size?

[smgm@xxxxxxx]

This seems like a dumb question, but here it is.  I used 
a 2" ball to take my 1970 27' Overlander to the storage 
lot (where I'm working on it), but now that I've gotten 
an permanent tow vehicle and I'm getting the receiver 
and the equalizer installed (the e-z lift 1000), I'm not 
sure what the correct size ball should be.  (2", 2 1/4" 
or 2 5/16").

My owners manual is missing pages 122-136 where this 
info is listed.

Thanks for the help!