Ford S197 Mustang Transmission Swap - Six-Speed Transmission Swap Kit

The S197's stock, heavy, two-piece driveshaft uses companion flanges at both ends, including a rather unusual configuration at the back. The kit replaces it with a one-piece aluminum shaft of correct length, having a more traditional slip yoke up front and using an adapter flange (not shown here) to bolt to the axle's pinion flange.

A final kit inclusion is this steel replacement transmission crossmember/mount combo, to mate the T56's F-body tailhousing to the existing unibody threaded holes.

Finally moving along to the installation portion of our program, here's the stock 3650 setup. The 3650 (unlike the T56) has an integral bellhousing, which necessitates removal of the exhaust H-pipe simply to make room to drop the transmission. Note the companion flange on the output shaft. The Viper T56 reverts to a more common slip yoke. As always, disconnect the battery ground to start.

Even before the exhaust came off, Don Walsh Jr. unbolted the driveshaft from its front and rear com-panion flanges. It's this unusual rear setup that requires the included adapter flange to mate with the new aluminum driveshaft.

The two-piece driveshaft also has a center support that must be unbolted from the unibody tunnel before it can be removed. The small tubular black brace visible here must also be unbolted to ease shaft replacement. By the way, the articulated factory shaft weighs a hefty 38 pounds; the aluminum replacement, a mere 15.

Before the H-pipe can come out, the rear pair of oxygen sensor harnesses have to be disconnected, along with the passenger-side front O2 sensor. The driver-side front sensor can remain.

In preparation to drop the 3650, the vehicle speed sensor (VSS) must be disconnected from the tailhousing, and its harness unplugged from the mounting holes along the left-side of the transmission. Also the three-bolt starter must be undone.

A block-plate is bolted to the front face of the transmission, but is sandwiched ahead of the crank-mounted flywheel. The arrows are pointing to the two bolts (one already removed), which must come out in order to free the transmission from the block-plate.

The shifter linkage arm and support arm must be disconnected from the 3650 (a look back at our earlier shot of the shifter setup might help visualize this.) For now, the shifter can remain bolted to the unibody, but it will eventually come out, as it's no longer needed.

Before getting to this stage, you'll have to disconnect the hydraulic clutch line at its junction at the left front of the 3650. Have a plug ready to stop-up the line during that step, as the clutch shares fluid with the brakes, using the master cylinder reservoir. When unbolting the tranny crossmember, support the 3650 with a jack so it can slowly be lowered after crossmember removal. The weight of the transmission will lower the rear, making it easier to get at and undo the bellhousing bolts.

To make sure the engine remains low in back once the tranny comes out, place a jack under the front oil pan bolts. Keeping the engine nose-high will make tranny removal and installation easier. Without this front jack, the engine will spring back to level once the 3650 comes off.

Seven 13mm bolts secure the bellhousing to the engine. The bottom four are easily reached; the top center bolt is best reached with a very long extension, or a number of short extensions used together. Bribe someone to help you lower the 3650 out once unbolted, because it won't make a nice hat.