Will a chevy 350 bolt up to a jeep transmission

We've discussed a lot of transmissions swaps in this column over the last few years, but we have neglected to mention one of the easiest and most popular swaps that can be done for GM cars and those of other manufacturers: the Turbo Hydra-Matic 350.

First introduced by GM as a replacement for the Powerglide in 1969, The TH350 was the stalwart of the GM transmission line until the mid-1980s. It remained basically unchanged through its entire life span until 1981, when an electric overdrive solenoid was added and the transmission was renamed the TH350C. Many enthusiasts prefer the extra gear and the gas mileage savings that the TH350 provides over the Powerglide, so the conversion from a Powerglide to a TH350 is commonplace with 1962 to 1968 GM owners.

TH350s are also ideal candidates for performance street rods with just about any kind of engine configuration. They are one of the most popular choices for converting from a standard to an automatic as well. Finding one of these transmissions, either used or new, is a walk in the park. GM produced so many, they should be as abundant as oil spots in the grass at your local pick-a-part. Automatic transmission fans will tell you that a TH400 is a stronger transmission, but the TH350 is shorter (meaning easier to adapt in smaller-bodied cars), and it saps a lot less horsepower from the engine to make it work. A typical TH400 drains almost 50hp to drive it, whereas a TH350 will operate at a loss of only about 35hp. The TH350 can take a beating too-with race modification, a TH350 can work with engines rated at more than 400hp.

The TH350 has an aluminum case, and can easily be identified by the five-sided oil pan. The pan has 13 bolt holes and the passenger-side rear corner is cut on a diagonal, making the fifth side. Otherwise the pan looks perfectly square. A vacuum modulator is attached to the valve body in the right rear, and the later electric TH350C versions have a four-wire plug connection on the left side of the case. These transmissions weigh about 125 pounds.

There were a couple of different bellhousing bolt patterns on TH350s. Chevrolet used one pattern, while Buick, Olds, Cadillac and Pontiac used another. There are also quite a few transmissions out there that have the CBC (Chevrolet-Buick Combined) pattern, meaning they are drilled for both bolt patterns. The CBC-350 will fit all the GM products, but if you cannot find one, your next best bet is to stick with the bellhousing that fits the Chevy, as most adapters are drilled for the Chevy bolt pattern.

The easy way to tell which bellhousing pattern you have is by looking at the top boltholes in the pattern. Chevrolets have a peak where the top bolts attach to the motor. The Buick-Olds-Pontiac-Cadillac bellhousings have a valley at the top of the bolt pattern. CBC-350s will have both the peak and valley bolt pattern on them.

The pre-'81 TH350 uses a detent cable to activate the gearshifts and passing-gear kickdown. You must use a detent with these units, or the transmission will not have a passing gear, plus the shifts will be very sluggish. The TH350C and the CBC-350 use an electric kickdown solenoid.

Whether you decide to try to find a regular TH350 or a TH350C depends on the type of driving you do. If you are on the highway a lot, using the electric torque converter lockup can mean fuel savings, but you will sacrifice torque converter life expectancy if you do not add additional transmission cooling. The lockup torque converters tend to overheat if you're not careful. Because the lockup is activated by a distributor signal, it is recommended that you grab the distributor from the same donor car as well.

Externally, all the TH350 transmissions look the same; however, internally there are some differences. Depending on the engine size of the car the transmission was removed from, it can have anywhere from 10 to 18 friction discs and 10 to 18 steel clutch plates inside. When given a choice, always select a unit from the larger vehicle or engine over the smaller. The rule of thumb here is: the bigger the engine and the heavier the vehicle, the more clutch plates used. You will find the TH350 with 6-, 9- and 12-in. tail housings, so it would be a good idea to get a measurement of the space you have available before searching for a replacement. Overall lengths are 27-11/16-, 30-11/16- and 33-27/32-in. respectively. Other dimensions for this transmission are available on our website (www.hemmings.com/parts-locator) at the Parts Locator link.

Ratios on the TH350 are consistent throughout its production:

First gear, 2.52:1; second gear, 1.52:1; third gear, 1.00:1; reverse, 1.93:1.

An aftermarket low-gear planetary can be purchased that will bump first gear up to an optional 2.75:1, if a taller first gear is desired. As we said before, finding one of these units should be a no-brainer. But for reference here is a list of vehicles that used the TH350 as original equipment:

1969-'84 Buick, Chevrolet, Olds and Pontiac full-size cars

1969-'81 Buick, Chevrolet, Olds and Pontiac A-body, G-body and F-body cars

1973-'79 Buick, Chevrolet Olds and Pontiac X-body cars

1969-'78 Riviera

1975-'82 Corvette

1975-'80 Buick, Chevrolet, Olds and Pontiac H-body cars (Vega, Monza, Skyhawk, etc.)

1981-'82 Cadillac Fleetwood and Deville (CBC-350 and TH350C versions)

1973-'85 Chevy and GMC 2- and 4WD pickups, Blazers, G-10, G-20 Vans and Suburbans

As you can see, you are looking at literally millions of potential donor cars. When you find one that you want to use, it would be a good idea to grab the torque converter and the driveshaft from this donor car too, especially if you intend to put the TH350 into a non-GM car. You will also need the slip yoke from the front of the driveshaft to adapt the Spicer 1310 series driveline to your project car. Spicer also sells a new yoke for TH350 or Powerglides, Spicer part number 2-3-4911X. And grab the flexplate, so you will be sure you have the proper style for the transmission you are getting. Some flexplates are weighted while others are not. And, if you are converting from a 3-speed standard to the TH350, you are going to need a steering column or floor shifter to go with the transmission too.

With any of these types of conversions we strongly suggest that you carefully inspect a salvage yard unit before installing it in your car. We do not recommend that anyone drop a junkyard transmission directly into a car without at least some minimal internal inspection, the changing of the filter screen and a transmission system flush treatment. Give your investment a fighting chance by starting out its new life in good condition. You will want to inspect inside the TH350 to see how many friction and steel plates it has and the condition of the other internal components anyway, so don't just grab one and go.

Exchanging a Powerglide for a TH350 is a pretty basic swap. Because the transmission lengths are the same and the positioning of the crossmember can be easily modified, you need only change the transmission mount, add transmission cooler lines and change the shift indicator bezel to a TH350 shift pattern to complete the exchange.

The stock Powerglide shifter will work on a TH350 with some adjustment, or floor console conversion kits are available from numerous aftermarket suppliers. Shifter cables to replace the existing linkage and neutral safety switches to complete the conversion on 1964-'72 A-bodies are also available. New "horseshoe" style floor shifters can also be purchased for floor-shift applications. Conversion linkage kits for column-shift cars to fit a TH350 into any car with an automatic on the column can also be purchased through aftermarket suppliers.

Some crossmembers, particularly on X-body GM cars, may have to be modified for clearance on the front lip area of the crossmember. Powerglides and the TH350 share the same 27-spline output shaft used in cars and two-wheel-drive trucks, so your existing driveshaft will fit right in.

Street rodders already know that the TH350 is a convenient automatic transmission choice for drop-in drivetrains. While originally used in many small-block V-8 and V-6 applications, the TH350 will also connect to aftermarket 502 performance motors that are now being offered.

For non-GM enthusiasts there are also adapter plates and scatter shields available to bolt a TH350 onto just about any classic or muscle car on the road today. Although these adapters can be expensive, they will save you hours of time and effort, not to mention brain overload.

For 1953-'64 Buick owners, adapters are available to equip your nailhead engine or straight-8 with this transmission. Lincoln and Edsel builders can utilize the TH350 on 1950s V-8 engines as well. There are even adapters for Studebakers, 1955-'64 Cadillacs and Pontiacs, including early straight-8-cylinder engines.

All configurations of Chrysler 6- and 8-cylinder engines, whether a 1950s poly, early Hemi, or more modern "A" or "B" block can be adapted to accept the TH350. Even the older stovebolt GM 6-cylinder engines and 6- or 8-cylinder AMC vehicles can benefit from the addition of a TH350. The TH350 is a popular exchange transmission for early Jeep four-wheel-drive enthusiasts, because of their short profile and their ability to easily accept multiple four-wheel-drive transfer cases. Studebaker, Hudson and International engine adapters allow a TH350 to be mounted behind them as well.

Many performance upgrade parts are available for this unit, too. In addition to the low-gear planetary mentioned earlier, you could also purchase high-stall torque converters and shift improver kits for the valve body. Aftermarket transmission parts suppliers offer improved intermediate and kickdown bands.

We would strongly recommend that the shift-improver kit be used as part of this conversion. The kit will address concerns enthusiasts have with the TH350 having a "wishy-washy" shift. It is also recommended that you use steel tubing for the vacuum hose to the modulator instead of rubber tubing. The length of the tubing could cause rubber hose to collapse under constant vacuum over time.

Looking into what you can expect to pay for a TH350, we called our local salvage yard. Used units are as inexpensive as $150 to $350.

You can find good rebuilt units already prepared for as little as $550 to $800. Most rebuilt transmissions will come with a six-month warranty, too. Used driveshafts can run between $35 and $100 if you cannot re-use your old one. Add on a new transmission mount ($15), a shifter adapter kit ($100) and a new backup switch ($45), and you can see that the cost for doing one of these conversions can still be between $600 and $1,100. You should have it completed in a weekend, if you get the parts together beforehand.

Installation into your non-GM car will be a little more expensive, because of the cost of the adapters. But, even with the adapter figured in, you could still expect to complete this conversion for between $1,000 and $2,000. So sometimes it can be less expensive to select the generic multi-use transmission over one of the less used or more complicated ones.

The TH350 will be a lot less work to install as well, and my time can be worth it's weight in gold, especially when the lawn needs mowing. And are those leaves falling out of the trees already?

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