You can use 94-98 Axles if you run SN95 Discs out back.
You could run drums with them also.. They will also set your wheels further out even with the fender lip..
I know my C clip elims had to be pressed to a different distance from the flange depending on weather or not I had disks or drums. To me it would seem like you would need the shorter axle from the ranger for the drums to work, rather than having a longer axle from an SN95 which would seem to position the flange to far away from the brake shoe.
Edit: Splines look fine for used axles, really you just need to look and see if they are start to twist.
Those mustang axles if I remember correctly are 3/4 inch longer than what you need. You will have to get the brackets and brake equipment off of the same kind of vehicle and I would definitely not run anything wider than a 245 tire. I'm running 255 tires on mine with stock length axles and they are getting close.
There are a ton of sites with the conversion info. You can use Ranger and Aerostar axles but there is a specific side you have to use and get two of them due to the differential begin offset. I'm not gonna say what side I think it is on both because I'm not quite sure, would have to look itup again. If I find the stuff I have printed up on it, I will shoot you the links. They have step by step instructions for disc or drum along with parts lists
You can't run drums with those axles.
If you want drum brakes, you need to run ranger/areostar axles or aftermarket axles specified for stock fox lenght.
the only way you could use those axles is if you ran the SN95 disk setup out back. Even so, the only axles you can use are 94-98 in the rear. In 99, ford widened the rear end. The disk brake hardware is the same 94-04, but the axles are longer for the 99-04's and won't work in any 8.8 unless it's the wider 99-04 8.8 axle.
Just to recap....
5-lug drum = ranger/aerostar/aftermarket fox lenght axles
5-lug SN95 disk = 94-98 axles.
(another option is using the north race car brackets with the ranger/aero/aftermarket axles to give you SN95 disks....on fox width axles. Basically if you start out with 5-lug drum, you can upgrade to disks later on down the road by using the aftermarket bracket kit and the sn95 parts)
any more questions
You could run drums with them also.. They will also set your wheels further out even with the fender lip..