I'd call one or the other or all of these folks.
http://www.drivetrainspecialists.com/http://www.ringpinion.com/http://www.dynatrac.com/ (could be they made it?)
They all know their axles and hopefully can point you in the right direction, or know right off what it is and the details.
You could legitimately inquire about 3.31 gears and want to know for sure that this axle is what you think it is.
The calipers may be OK if sealed up, otherwise probably have some moisture, could flush them and see what comes out. Or look into replacement ones, may be so cheap it's a mistake not to swap them out.
Grigg
