Ford Mustang Rearend Modifications

Nearly 90 percent of the thousands of rearends built by Currie share some of the same parts, including the housings and axles. Other parts include the 9-Plus round-back, heavy-duty housing, as well as 31-spline axles built to the stock overall width and pinion offset specs of the car. Heavy-duty 2-1/2-inch-wide leaf-spring pads are installed in the stock location for easy bolt-in installation. The housing includes all third-member studs installed and the Torino-style, late-model, large-bearing housing ends. The axles include the stock 5-on-4-1/2-inch wheel-bolt pattern; installed wheel studs; 1/4-inch-thick, heavy-duty bearing retainer plates; and tapered, pressed-on, Timken-style wheel bearings. The crate rearends are shipped in four separate cartons, which include the housing, the third member, axles, and brakes. Basic assembly is required. Shown here are the housing, axles, and third member for the typical vintage Mustang application (PN FDM6466X for '65-'66, FDM6770X for '76-'70, and FDM7173X for '71-'73).

Standard 11x2-1/4-inch drum brakes include new hardware and shoes assembled on the backing plate, and new drums.

For decades, the Ford 9-inch rearend has been the standard by which all other axles are judged. First introduced in 1957, it was used throughout the entire '65-'73 vintage-Mustang era on cars with optional higher-output engines available, beginning with the K-code Hi-Po 289s in the first '64-1/2s.

For '66, K-code cars were the only Mustangs equipped with the 9-inch axle. For '67, cars equipped with a 390 joined in. From that point forward, mainly '68-'73 big-block (390, 428, and 429) Mustangs were equipped with a 9-inch. Cars with 351Ws and 351Cs also got this legendary piece of hardware. The only small-block Mustangs to get a 9-inch were '69-'70 Boss 302s and the previously mentioned '65-'67 K-codes. Mustangs with 289s and 302s were equipped with an 8-inch rearend.

The optional rear disc brakes on the Currie crate rearend are 11-inch Explorer units. They include a semigloss backing plate/caliper mounting bracket with an assembled drum-style parking-brake system (center). Calipers, pads, rotors, and all other required hardware is included. Although not sold by Currie, other brake kits that fit the crate rearends include those offered by Baer, SSBC, and Wilwood.

It's acceptable to say that high-performance Mustangs and 9-inch rearends go together like ham and eggs-it's a fact not lost on Currie Enterprises. The company has implemented a crate rearend program to reduce the time needed to ship one. Instead of waiting several weeks for it to be custom-built and shipped, Currie can get one out the door in a day or two. Roughly 85-90 percent of the custom-ordered rearends share the same housings and axles, along with other components and parts common to Mustangs. The company keeps these across-the-board pieces on the shelf before a rearend is ordered. The program will be of real interest to Mustang owners who want to upgrade.

Along with vintage cars, Currie offers applications for part of the late-model spectrum. This includes '79-'93 Fox-body cars, as well as a complete and assembled package for '05-'07s.