I put an Explorer 8.8 in my '66. One side of the Explorer housing is like 2.93"? (I can't remember exact number) longer than the other side. You need to cut it down to the same length as the shorter side. Then you use 2 of the shorter axles. There used to be a great write up that someone posted on the internet about this project, but I can't find it. It wasn't too difficult, but I have a friend who has experience welding the rear end up straight. I think I would have screwed that up. I did the whole thing for less than $300. That included rebuilding the 3.73 traction loc, a junk yard aluminum drive shaft, new bearings, seals, etc.
The down side is questionable strength compaired to a 9", and it is about an inch narrower than the stock 8". I had to use spacers. For the price though, I had to give it a try.
Good luck.
Here is a chart you can use to see what you are looking for as a replacement.. This is difficult to read in this format but if you would Have ms excell I can email the file to you. It is a work in progress. I add data to it everytime i find it. Also this is hub to hub width. Usually you can get away with up to 1.5 inches wider. This is really the limit I have seen and usually that much means rolling your fenders. But for example I am using a 96 8.8 in my 69. I had to cut off the axle mount and put new perches on. But the rest is getting used as as and I will be running 17x9 wheels. I test installed and all of my clearances we tight but within limits. I may have to do a little inner fender work where the spare tire mount to prevent rubbing.
Rear end Width,Mustang,Cougar,Commet,Granada-Monarch,Ford Ranger,Explorer,Aerostar,crown vick,T-Bird
1965,57.25,,,,,,,,
1966,57.25,,,,,,,,
1967,59.25,60,59.25,,,,,,
1968,59.25,59.25,59.25,,,,,,
1969,59.25,59.25,59.25,,,,,,
1970,59.25,59.25,59.25,,,,,,
1971,61.25,59.25,59.25,,,,,,
1972,61.25,,,,,,,,
1973,61.25,,,,,,,,
1974,,,,,,,,,
1975,,,,58,,,,,
1976,,,,58,,,,,
1977,,,,58,,,,,
1978,,,,58,,,,,
1979,,,,58,,,,62.8,
1980,,,,58,,,,62.8,
1981,,,,,,,,62.8,
1982,,,,,,,,62.8,
1983,,,,,,,,62.8,
1984,,,,,,,,62.8,
1985,,,,,,,,62.8,
1986,58.75,,,,,,,62.8,
1987,58.75,,,,,,,62.8,
1988,58.75,,,,,,,62.8,
1989,58.75,,,,,,,62.8,
1990,58.75,,,,58.75,,59.75,62.8,
1991,58.75,,,,58.75,,59.75,62.8,
1992,58.75,,,,58.75,,59.75,62.8,
1993,58.75,,,,58.75,,59.75,62.8,
1994,60.25,,,,58.75,59.75,59.75,62.8,
1995,60.25,,,,58.75,59.75,59.75,62.8,
1996,60.25,,,,58.75,59.75,,62.8
1997,60.25,,,,58.75,59.75,,62.8
1998,60.25,,,,,59.75,,62.8
1999,61.0625,,,,,59.75,,62.8
2000,61.0625,,,,,59.75,,62.8
2001,61.0625,,,,,59.75,,62.8
2002,61.0625,,,,,59.75,,62.8
2003,61.0625,,,,,59.75,,
2004,61.0625,,,,,,,
2005,,,,,,,,
2006,,,,,,,,
2007,,,,,,,,
2008,,,,,,,,
2009,,,,,,,,
2010,,,,,,,,