You definetly have to dig it up to see what you'll need. Maxi-Paws have two inlets. You need to see how it's connected. Nothing's standard. Swing joints are probably your best bet.
www.sprinklerwarehouse.com/v/vspfiles/search/search2.asp?Extensive_Search2=N&keywords=hunter+swing+joints
You could convert your existing Maxi-Paws to PGP's without doing any digging with retrofit rotors. You would need a tool to unscrew the innards of the Maxi-Paw. Clean it out with a hose first.
www.sprinklerwarehouse.com/Hunter-PGP-ATR-PGP-Impact-Replacement-Rotor-p/pgp-atr.htm