I have searched through this forum looking for a diy article on removing and replacing the transmission. I did not find one so i decided to write one.

1982 300sd 617 engine 722 transmission DIY removal and installation

First: disconnect the battery since you will be working around the starter.
You may also want to wash the underside of your engine and transmission first using something like GUNK... You may or may not want to remove the transmission fluid. Your choice. (I always remove the trans fluid) On the valve cover disconnnect and remove the kickdown cable and disconnect the vacuum hose to the top of the IP...

Tools required
1 or 2 floor jacks, I actually used 3 this time
Large blocks of wood
4 jack stands, 2 of which must be the large adjustable type.
1 transmission jack... harborfreight.com 54 dollars

I use 3 or 4 different ratchets with the sockets already in place.
1 17 mm (Cross members)
1 15 mm
1 13 mm (removing the torque converter)
1 10 mm for one sensor that is connected to the rear driverside of the tranny..

You will need 3 allen wrench sockets
1 10 mm (this is for the starter)
1 8 mm (this is for the drive shaft)
1 5 mm (this is for the clamps holding down the transmission hoses)

You will need 3 wrenches and some socket extensions
1 17 mm
1 15 mm
1 13 mm


First: find a good level place to do the work. Now using the floor jack, the wood and the large jackstands.... jack the front of the car and place the jack stands under the jacking points just behind the front wheels... there are pads there.

Second: remove the forward cross member.... This is held in place with 6 17 mm bolts.

Third: Now remove the rear cross member. It is attached to the transmission with 2 13 mm bolts in the center of the cross member. Remove all bolts.

Fourth: At the rear of the transmission is a flex disk which connects to the drive shaft. 3, 8mm hex bolts connect to the tranny and 3, 8mm hex bolts connect to the drive shaft. Remove the 3, 8mm hex bolts that connect to the drive shaft. You will need a wrench to hold the bolt on the oppsite side. 17 mm wrench. With much effort you will be able to remove 2 of these bolts and one will probably be impossible for you to access. Now jack the rear of the car and place small jack stands. Rotate the rear wheels until the third 8mm bolts comes into access. With the rear wheels up the drive shaft will try to turn as you try to loosen. So The wrench will have to help hold the drive shaft. The drive shaft is 2 parts and will slide towards the rear wheels with much effort or on the older cars you will have 2 drive shafts connected with a center bearing. Mine had the center bearing... so disconnect the forward shaft. This will require you to remove the exhaust heatshield. Now inspect the rubber flex disk. This item has metal sleves held in a hard rubber disk. If the metal sleves have any play then replace the flex disk with a new one. (This is not an easy job) (warning: transmission will droop 6 or 8 inches on this next job... I blocked it up with wood)


Fifth: Now remove the 6 13 mm bolts that hold the torque converter to the engine. You will need a ratchet with a small extension. There are 2 windows that allow you to view the torque converter. One is a part of the transmisison and it is used for accessing the Torque converter drain. The other window is part of the engine and it is used for accesing the torque converter bolts. You will have to rotate the engine. You can do this with a 27mm ratchet from the crank or with a ratchet at the power steering pump. Only rotate the engine clock wise. You will need a flash light. Now remove these 6 bolts. (this is not an easy job)

Sixth: Now remove the things that connect to the transmission, Gear shifter, Transmission cooling lines and clamps. (they use banjo bolts) Exhaust clamp, vacuum connection, Transmission filler tube, On the right side of the transmission is a large electrical connection... This large electrical connection requires you to push up the white plastic retaining clamp becareful...study this carefully remove this, and on the rear of the transmission is a connection as well. Remove all these. remove the ground connection and remove the exhaust bracket connection.... I loosened the exhaust clamp portion and rotated out of the way.

Seventh: Unbolt the Transmission from the Engine at this point it really best to have a floor jack with a transmission attachment (Danger, You can drop the tranny on yourself and I have also heard of someone cutting off a finger by getting it caught between the tranny and engine.) You will be sliding the transmission straight back being cautious with the torque converter. (this is why you had to remove the drive shift to make room for the tranny to go back toward the rear of the car.

Now if your an expert mechanic you have done this in about 5 hours.... if your like me this has taken you all day.... so tomorrow we install the new transmission.....

the installation is just the reverse of all this.... execpt you must becareful with the torque converter..... if there is metal debri in the pan replace the torque converter... if there is just brake band grit then you can rinse it out and reuse it.... the torque converter slides into the transmission 3 times... you could almost say there is three little clicks.... now a new transmission will have a rubber plug that will keep you from putting the torque converter in place.... you have to get this right.... and the torque converter should have a little play as you put it in place.... also rotate and wiggle. You dont want it in any bind.... now bolt up the transmission... then bolt up the torque converter.... always rotating the engine clockwise.... as you put the 6 torque convert bolts in place.....

Now refill with dextron tranny fluid.... probably 4 qts... and then add about 2 more once started....

congrats... you did it.....now drink a beer....

ask any questions and I will answer them if I have not been technical enough..