'"Just put a 9-inch in it!" That has been the rallying cry for Ford enthusiasts for more than 40 years. If there is an industry standard for rearend strength and durability, it has to be the Ford 9-inch. But the days of finding a Mustang-width 9-inch housing in the junkyard that you can use for a typical leaf-spring street machine are rare. Even the big rear-axle companies like Currie, Moser, and Strange now make their own housings rather than try to find decent cores. But there is an alternative-the Ford Mustang 8.8-inch rearend.
We were wrenching at Tim Moore's shop one afternoon when he suggested the 8.8 is the Blue Oval equivalent of the Chevy 12-bolt. The advantages of the Ford 8.8 are that it's light, durable (with a couple of upgrades), and, the best part is, there are thousands of them lying in junkyards right now, ripe for the picking at far more affordable prices than either the 9-inch or the Chevy 12-bolt. We did some research and discovered on Randy's Ring & Pinion Web site a list of no fewer than 24 different Ford vehicles that use the 8.8 rear-axle assembly. Not all of these are worthwhile options, but the list suggests plenty of choices.
Why should you care about the Ford 8.8? The biggest reason is there are thousands of Fox-body Mustangs with 8.8 rearends in boneyards all over this country that can be easily purchased for $100 or less. This rearend is lighter than a 9-inch and is as strong as a 12-bolt (except for the axles), and many Mustangs came from the factory with Traction-Lok limited-slip differentials. All you have to do is cut off the coil-spring brackets, weld on leaf-spring mounts, and perhaps add a different pinion snout, and you're ready to go with an inexpensive yet strong rear-axle assembly. It will never get any easier or cheaper than this.
For us, it started with a search for a performance replacement for the lame 8-inch rearend in our Car Craft '67 six-cylinder Mustang. The stock four-lug axles had to go and there was no good reason to invest in the weak 8-inch. We also had an 8.8 rear sitting in a wrecked '88 Mustang we bought for the 302 engine, and we discovered that the Fox-body Mustang 8.8 rear is a mere 31/48-inch wider than the stock 8-inch '67 Mustang rear. This led us to consider that this inexpensive 8.8 Ford could be used in all kinds of leaf-spring-equipped cars, like the '62-'67 Novas, early Camaros, and the '68-'74 Novas. Frankly, we don't expect a ton of Chevy guys to pick up on this idea, but that just leaves more 8.8 rearends for budget-strapped Ford guys to hoard. We're already planning on snapping up another 8.8 to go through in more depth that will eventually find its way into our '67 Mustang. But for now, let's see how this 8.8 stacks up as a swap axle and what parts are available to make it stronger.
The 8.8-inch Ford is an inexpensive alternative to the more expensive rearend choices for the budget-limited Ford performance enthusiast.
There are more similarities than differences between the Ford 8.8 and the Chevy 12-bolt. Add 31-spline axles to the 8.8 and you could make a case that the 8.8 is stronger than the 12-bolt and certainly more affordable.
The stock Mustang 8.8 uses this flat-flange-style pinion yoke. We're thinking of retaining this for our swap in the '67 Mustang. Hopefully the '88 Mustang driveshaft is long enough so that we can shorten it and use it in the '67 car. If that doesn't work, then we'll swap out the pinion yoke for a more traditional 1310- or 1350-style U-joint configuration.