Then money spent strengthening the 7.5 is better spent on a 8.8 IMO
79-93 5 Lug Ford Fox Body Mustang Conversions
To convert the rear end to 5-lugs you need to replace the 4-lug axles and drums with 5-lug units. The axles that are needed will be either off of a Ranger, Bronco II or Aerostar van.
From an '83 to '92 4 cylinder or 3.0L V6 Ranger/Bronco II with a 7.5" rear end you will need two driver's side axles. Only the driver's side will work as the pumpkin on these rear ends is offset and the axles are different lengths (you need the longer of the two axles). It should measure 29-5/32".
From an Aerostar you will need two of the passenger side axles from an 86 to 97 model.
The axles are all the same so they can be mix-matched (i.e. - one driver's side axle from a Ranger and one passenger side axle from an Aerostar).
You can use the brake drums from either side of the above listed vehicles but make sure that they are 9" drums. The 4.0L Rangers came with an 8.8" rear end with 10" drums - this will not work.
Be sure to check the axles to make sure they are not bent or worn on the bearing surface and check the drums to ensure that they are smooth or can be turned to no more than the maximum diameter.
Miscellaneous items for the rear include new brake shoes, fresh gear oil, RTV gasket maker to seal the differential cover and one additional lug nut for each
For the front
For the front you will need one each left and right side spindles, hubs, rotors and calipers from either a '94 or '95 V6 or V8 Mustang. The assemblies are the same for the V6 and V8 so either will work but it must be from a '94 or '95. This is because the spindle was moved out about ¼" - ½" on the '96 and later Mustangs. This will cause the wheel to stick out too far and possibly cause interference problems with the wheel well lip on the fender.
If you are getting the parts from a wrecker in a complete assembly then make sure that they include the Banjo Bolt that attaches the flexible brake line to the caliper. This will allow you to connect your existing brake lines to the SN95 caliper since the threads are different and the Fox Banjo Bolt will not thread into the SN95 caliper. Using the SN95 Banjo Bolt is the easiest way to do it rather than connecting the SN95 flexible lines to the Fox hard lines because they are different sizes and will require adapters (and the SN95 uses two different size connectors left and right side). Just use the SN95 Banjo Bolt on your flexible line for ease of installation
Miscellaneous parts needed for the front include new brake pads, one additional lug nut for each side, new cotter pins (4), new copper washers for the Banjo Bolts (4) and a 0.330" tall spacer (or washers totaling 0.330"). The last item is necessary to properly fasten the crown nut on the lower control arm ball joint/spindle connection.