How universal is the 7-1/4" axle

The 7.25 rear is a piece of crap. Better to upgrade to a 8.25 or 8.75 or a Dana 60.
But yes the 7.25 can be different, there is a sbp and BBP version which the BBP version is wider. There is also a suregrip (limited slip) unit that can be installed in one. My vote would be the 8.25 rear and install the rear disc brakes off a Jeep grand Cherokee.