I did search through many of my mags and went on line and couldn’t find the manufacturer of the newer stronger 8 in rear. I may have been dreaming, so I have to retract what i said about the 8 inch.
here is some info I found on it’s capabilities, some of which I copy and pasted here.
If you want to see the pictures and the rest of the thread on the subject, Here is the link. Only the pictures will show up on the original thread.
http://www.allfordmustangs.com/forums/classic-tech/148797-how-strong-8-inch-rear.html
The 8-inch rear end came out in 1962 [1962-1980]. The 8-inch 3rd members from '62-'66 are the weakest versions. Starting in '67-up, the 8-inch 3rd member case was revised [C7OW casting] to include more vertical and cross-webbing on the face of the case to strengthen it.
There are claims of people running these 8-inch rears with 400 hp, and they may be getting away with it, but these rear ends were not engineered to reliably handle that much power and torque --at least not without a lot of beefing up with [expensive] aftermarket parts.
All early V-8 Mustangs came with 8-inch rears except for the HiPo 289s --they came with 9-inch rears. The HiPo 289s were rated at 271 hp [Shelby 289s were rated at 306 hp].
The HiPo 289 carried over into the '67 model Mustangs. Even though the 8-inch 3rd member case had been revised by '67, Ford still did not use the revised 8-inch in the HiPo 289 Mustangs --they used the 9-inch.
Manual transmissions and sticky tires with lots of traction are not the only things that will kill an 8-inch. Most Mustangs suffer from wheel-hop, and this can also kill an 8-inch, even with regular street tires.
There are a few common failure points for an 8-inch; one is in the area of the input driving pinion support on the front of the 3rd member casting. The other is in the area of the pinion [spider] gears inside the differential, or with the differential main caps/bolts.
An example of a driving pinion support failure on an 8-inch [revised case] 3rd member:
http://img387.imageshack.us/img387/7...dmemberrq7.jpg
An example of the main caps and main cap bolts breaking that lead to this disaster on this 8-inch [revised case] 3rd member:
-
http://img387.imageshack.us/img387/2...n8inchclq1.jpg
-
http://img383.imageshack.us/img383/6...n8inchaas3.jpg
-
http://img362.imageshack.us/img362/6...en8inchru7.jpg
-
http://img387.imageshack.us/img387/1...n8inchbvn9.jpg
I suspect the reason why so many people run 8-inch rears, in applications it wasn’t really designed to reliably handle, is because a [wrecking yard] 8-inch is much easier to find in the right width for an early Mustang than a 9-inch of like parameters. It’s your car and your money, so only you can make the decision of running a rear end that might last, or to run one that will give you no worries.
An 8-inch, beefed up with expensive aftermarket parts, is only as strong as your base-model, stock-configured, run-of-the-mill wrecking yard 9-inch rear.
8-inch rear ends only came with differentials that had 2 pinion gears inside. A 9-inch could have either a 2-pinion differential, or a much stronger 4-pinion differential to distribute the force over a greater surface area.
http://forums.mustangandfords.com/70/8354548/mustang-fords-drivetrains/finding-strength-in-fords-8-inch-rearend-article-i/index.html
**
