Ford 8-Inch Differential Build

Our resident technohead and technical editor Mark Houlahan is building a '66 Mustang hardtop for his personal enjoyment. It will be Anniversary Gold with a 289 V-8. Because Houlahan wanted his unusual steed to appear stock on the surface, using an 8-inch rear axle for the rolling stock was his only choice in the correctness department-it just made sense. When Houlahan called me and expressed his interest in a restified approach to his restoration, we talked about the rearend. We both agreed that the 8-inch differential doesn't get the credit it deserves for reliability. And for engines producing less than 350 hp, the 8-inch is a logical solution. What's more, an 8-inch was logical for Houlahan's hardtop.

When I called Ray Currie of Currie Enterprises, he had the solution for Houlahan's challenges. First, step up to a '67-and-up axle housing, shortened to the correct width for a '65-'66 Mustang. Second, grab a '67-and-up chunk and stuff it into the modified housing. And finally, fit the iron with a supersmooth limited-slip differential from Currie Enterprises. The folks at Currie make it easy because they can build a rearend to your specifications. They will also give you valuable advice along the way.

1 This is the super-eight package from Currie Enterprises for a respectable '66 'Stang. The package includes a custom-made axle housing, 28-spline axle shafts, new 10-inch drum brakes, and the Currie 3.25 differential with limited-slip.		2 An exploded view of the heavy-duty Currie 8-inch unit shows the 3.25 gears, a limited-slip differential, new bearings and seals, and the shims necessary to adjust the ring-and-pinion. We chose the '67-and-up casting because it has more webs and plenty of meat around the pilot bearing and shaft.
3 Ray Currie of Currie Enterprises checks the axle shafts for trueness and integrity, and then fits them with new bearings. This is a 28-spline axle shaft. When we asked Currie about the stronger 31-spline shaft, he commented that the 8-inch differential would fail long before a 28-spline shaft would. We opted for the standard 28-spline shaft.	4 The difference between a '65-'66 Mustang axle housing and a '67-'70 housing (aside from width) is the axle tube size. The '65-'66 axle tube (not shown) tapers toward the flange. On the '67-and-up, it's a straight tube (shown). Currie can build you a large tube housing for your '65-'66 Mustang.	5-a Axle seals need care.
5-b Run a thin bead of silicone sealer around the seal's circumference, and then drive it into the axle flange as shown.	6 The axle flange is lubricated as shown with molybdenum grease. This prevents the axle bearing from corroding at the flange.	7 New Currie 10-inch drum brakes make the ride. These drum brakes are 2 inches wide for better braking efficiency.