How universal is the 7-1/4" axle

I'm looking for one axle for my 67 Barracuda. If I see a car with a 7-1/4" rear end, how universal are the axles? How many years was this rear end used? From the first year to the last year, are the axles the same? Are they all SBP? If the brakes are 9" or 10", are the axles the same?