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The best solution to the problem is to install an aluminum driveshaft. Not only is it balanced true, it's lighter too. Plus it doesn't rust, so when you stick those chassis mirrors under your car, it'll still look good. We decided to keep it in the family and went with a Ford Motorsports aluminum driveshaft (#M4602G) that we saved some bucks on by getting it through Summit Racing. We figured that while we were in there, we'd swap out the extension housing seal.

Old vs. new.

Jack the rear of the car up. Get as much clearance as possible. Chock the front of the car securely. The reason for this will become self-evident shortly.

Hey, while you're in there, think about changing your transmission fluid and filter. You should really do it every 20,000 miles you know. Slacker.

The driveshaft is connected to the yoke at the differential with four bolts, all of them 12mm. The clincher is that they're 12-point heads, so you've got to have 12-point sockets or you're, like, screwed dude. But the really fun part is that you can't fit a socket wrench in there! Ha ha!

There is a solution. What you need are called socket caps, and Sears sells them under their Craftsman name in three-per-bag, one each for the three common drive sizes, under part number 43303. Basically, they're hexed plugs that go onto the end of a socket, allowing you to put a standard open or box wrench on a socket.

So do this to a 3/8-drive 12mm 12-point socket, put a 9/16" box wrench on that, and.... do nothing. These bolts are threadlocked from the factory. Try using your leg. That oughta get it.

Once you've got the first, you'll soon find that you can't access any others. To get at them, put the car in neutral and rotate a wheel until another bolt is accessible (chock the wheels didja?). Then put the car back in park and repeat the procedure. Do this until you've removed all four bolts and the driveshaft hits you on the head.

Here is one of the difficult 12-point bolts.

Well, okay, try to avoid that part.

With the four bolts removed, the driveshaft just slides out of the transmission extension housing.

Before continuing, think about replacing the extension housing seal. Ours was already leaking at a measly five years of age; if yours isn't leaking yet, it probably will be soon. So grab a seal from a Ford dealer (or from any parts store, really) and pick up a seal puller while you're there.

The housing seal comes out pretty readily with the seal puller. Some people use a screwdriver to get it out, but that's a good way to be frustrated for a couple hours: get the seal puller. You'll thank us.

Use a hammer to tap the new seal into the extension housing. Be gentle; you don't want to bend it. But some patience will get it in there straight.

Extension housing seals. One's new. The other isn't.

Take the new driveshaft under the car and try to approximate its orientation to the yoke bolt holes. Slide the end of the shaft into the extension housing and engage the teeth. Don't force it as this could cause a lot of expensive damage -- it'll engage smoothly when you get it right.

Attach the bolts. Use threadlocker on them, then install the bolts using the same technique that got them off.

Give that threadlocker some time to dry, and that's it! You're ready to roll!

Just for kicks, before installing the new driveshaft we weighed them. The stock steel Ford driveshaft was 22.5 lbs. and the aluminum Ford Motorsports shaft was 14.0 lbs., a significant 8.5 lbs. lighter! The effect of the weight is magnified in a driveshaft, since it spins; the lighter shaft requires less energy to overcome its inertia. Plus, it looks way cool and won't kill us at 100 mph, both big selling points. With the ease of installation, there's really no reason to avoid doing it!