Practically any transmission GM produced will fit in your Malibu. I will cover the more popular automatic transmission swaps (manual is covered in another tech topic). First, let’s start with a table showing the dimensions of the most common automatic transmissions.
| Transmission | Width at Bellhousing | Overall Length | Front Edge to Mount Pad |
| Powerglide | 19″ 19″ | 25 23/64″ 27 9/16″ | 20 9/16″ 20 9/16″ |
| Turbo 350 | 19 1/8″ 19 1/8″ | 27 11/16″ 30 11/16″ | 20 3/8″ 20 3/8″ |
| Turbo 400 | 20″ 20″ 20″ | 28 3/8″ 33 27/32″ 38 1/8″ | 26 15/16″ 26 15/16″ 26 15/16″ |
| 2004R | 19 1/8″ | 27 11/16″ | 27″ |
| 700R4 | 20″ | 30 3/4″ | 22 1/2″ |
| Vette 700R4 | 20″ | 29 7/8″ | 22 1/2″ |
TH350, Powerglide, Saginaw and Muncie
All of these use the stock TH350 crossmember and the stock length driveshaft.
TH400 or 2004R
At first, I thought this was an easy swap. I read an article that said you can get the crossmember from any g-body equipped with a 2004R and it will bolt right up to the TH400. Well, that is partially true. IF you have a 84 OR LATER G-body, it will work. But, the 78-83 G-bodies never came with the 2004R. The frame rail crossmember mounts are different from the latter year models. The latter year G-bodies frame mount locations that extend further back (toward the rear of the car). Since the 78-83 models do not have these, you will not be able to use the factory crossmember (unless you make the frame extension piece). Other options are to either get a crossmember from G-Force Performance, get a “universal” crossmember, modify/fabricate your own, or make a frame extension piece and use the stock TH350 crossmember. I modified mine by removing the mount pad from the front side of the crossmember, then using 1/4″ thick steel plate, welding it to the back side of the crossmember. I then drilled an elongated hole for the transmission mount bolt to go through. Not too difficult to do yourself if you have access to a welder. Otherwise, you will need to get someone to do this. The TH350 driveshaft will either need to be shortened, or you can use a stock one from a later model G-body that had a 2004R transmission. Remember, you will have to use the yoke from the TH400 on the new driveshaft.
700R4
Go to this site for all the details: http://www.angelfire.com/80s/monte/transmis.htm
T5 – 5 speed swap
Check out these links for information on swapping a T5 into your Malibu/A-Gbody:
Installing a T5 Transmission into a 78-88 A/G Body by Marc Hichens
Installing a T5 Transmission into the Monte Carlo SS by J. Matthew Daugher
T56 – 6 speed swap
Check out John’s excellent site where he swapped a LS1 and T56 into his Monte SS:
http://www.montecarloss.com/ls1montecarloss/
DriveShaft Issues
If you are swapping a in a different transmission for racing or to back up a more powerful engine, you may need to upgrade your driveshaft. I got a HD driveshaft with a 3.5″ diameter and 1330 series ujoints made at a local driveline shop. You can go to Denny’s Driveshafts to see EXACTLY how you need to measure for your new driveshaft. They also explain the differences in u-joint series (sizes).
If you see any info that is incomplete or incorrect please contact me!