Tom 63-69 is the same size from drum to drum. 63-64 are a 14 spline axle. 65 and up went to 30. 70-87 is a little bit wider then ours. You can still use this axle you will just have to get the correct back spacing wheels. Also 71 they changed to 5 lug. 63-70 is 6 lug. I hope this helps some.
check out this website.
www.car-parts.com just look for axles in texas and you'll find a bunch.
what are your plans with the one you have now and what gears in it?