JEGS
Transmission Crossmember for GM TH350
555-640600
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G-Body Crossmembers
JEGS 555-640600 Transmission Crossmember Features:
- The double-hump design allows dual exhaust upgrade for your vehicle
- Compatible with the following applications: 1978 - 1988 GM G-body vehicles including Chevrolet Malibu, Monte Carlo, Buick Regal and Grand National, Oldsmobile Cutlass, and Pontiac Grand Prix. will not fit Olds cutlass Supreme or Chevy El Camino models
- Black powder-coated steel for strength, great looks, and long life
- Must have upgrade for transmission swaps
JEGS 555-640600 Transmission Crossmember Note:
- Crossmember is designed for the 1978-88 G-Body that was originally equipped with a SB-Chevy. Does not fit Oldsmobile Cutlass Supreme, Chevrolet El Camino, or some Buick Regal Models. Engine and transmission swaps may require some additional modifications & fitment of components. Hardware is not included.
FAQ
What does a transmission crossmember do?
- A transmission crossmember plays a crucial role in supporting and aligning the transmission in a vehicle's chassis. Specifically, the G-Body TH350 crossmember, part number 555-640600 from JEGS, is designed to provide a secure mounting point for the TH350 transmission in G-Body vehicles. This crossmember helps distribute the weight of the transmission, maintains drivetrain alignment, and reduces stress on mounting points, ensuring proper functionality and longevity of the transmission.
How much power can a TH350 handle?
- The TH350 transmission is known for its robust design and ability to handle moderate to high levels of horsepower and torque. While exact power handling capabilities can vary depending on factors such as build quality, upgrades, and driving conditions, a properly maintained and configured TH350 can reliably handle up to approximately 450 horsepower and 400 lb-ft of torque in stock form. However, performance enhancements and aftermarket upgrades can significantly increase its power-handling capabilities.
Are there different TH350 transmissions?
- While the TH350 transmission has undergone revisions and improvements over its production lifespan, there are not significantly different variations like with some other transmissions. However, there may be subtle differences in internals, valve body configurations, and torque converter specifications between model years and applications. It's essential to select the appropriate TH350 variant for your vehicle's needs, whether it's for a stock replacement or a high-performance application.
What is the length of a TH350 transmission?
- The length of a TH350 transmission can vary slightly depending on the specific model and configuration. However, on average, the TH350 measures approximately 21.75 inches in length from the bellhousing to the tail shaft housing. This compact design makes it suitable for a wide range of vehicles, including G-Body cars. Ensure proper fitment and compatibility by selecting the appropriate G-Body crossmember, such as the G-Body LS swap crossmember TH350, available at JEGS.com.
Specifications:
Part Type
Product Line
Amount of Drop
Stock
Bolts Or Studs Included
No
Crossmember Finish
Black powdercoated
Crossmember Material
Steel
Mounting Bracket Included
No
Package Depth
4.00
Package Height
49.30
Package Width
9.50
Part Category
Replacement Parts
Part Fitment
Direct Fit
Quantity
Sold individually
Shipping Weight
13.35
Transmission Crossmember to Frame Bushing Included
No
Transmission Mount Included
No
Width
45.28 in (1150.11 mm)
640600 is rated
out of
5 by
67.
Rated 5 out of
5
by
Donut man from
Cheapest 4l80e mount
Bought this with the plan to hack it up until it worked for a 4l80. Turns out you barely need to do anything! Buy two of the recommended crossmember extension, drill some new holes and it bolts right up. Good pinion angle, lots of room to floor.
I only bought the one extension so I had to cut it in two and weld the other part to the frame rail. You do need to cut out a tab on the inside of the frame (picture #4), not sure what used to be there.. Not quite a bolt in crossmember but an hour of measuring and drilling it works great for 1/4 the cost of all the other ones!
Date published: 2023-11-28
Rated 5 out of
5
by
Nick from
Perfect
Purchased this along with the jegs gbody headers and dual exhaust. The crossmember was the easiest part of the install.
Plenty of clearance for the exhaust.
Says doesn't fit oldsmobile cutlass Supreme, but fit my 1980 Calais like a glove.
Date published: 2023-07-01
Rated 5 out of
5
by
El camino from
Crossmember
I have a 1983 El Camino I put a 355 small block with a 350 turbo transmission bolt it up just fine
Date published: 2023-02-20
Rated 5 out of
5
by
D and D Performance Engs from
Fits like it was from GM. 1980 Cutlass Supreme
Even tho it says it won’t fit, it does. No clearance issues with the floor, all 4 bolt holes lined right up. Easiest thing I’ve installed on this build.
Date published: 2023-02-12
Rated 5 out of
5
by
Anonymous from
Jegs has all the best parts for great prices!
Great bang for you buck! Good deals for everything automotive!
Date published: 2022-12-24
Rated 5 out of
5
by
Chris from
A very well built crossmember for the El Camino.
After reading the reviews I took a chance on buying this part even though the description states that it doesn't fit the El Camino. For my application which is a 1978 El Camino 305 V8 it worked perfectly. I only had to enlarge the 2 driver side bolts and center slot slightly. I recommend replacing your center transmission support\mount with a new one. Also grab you a set of 4 grade 8 bolts, 8 washers and 4 lock washers while you're at it. I'm running long tube headers so I removed the exhaust bracket from the crossmember.
Date published: 2022-06-06
Rated 5 out of
5
by
Mlj78 from
Great product.
Bought for 78 malibu fit perfect,good quality,nicely made piece
Date published: 2021-04-19
Rated 5 out of
5
by
a j classics from
fits elcamino
i don't know what's up with the no el camino fitment, but it fit my 85 perfectly with no modification. probably will not work with factory catalytic converter but dual exhaust is the main reason for installing it anyway. perfect fit with th350 trans
Date published: 2020-12-28
Will this fit a 1986 cutlass with a sbc 350 and th350
The Jegs 555-640600 crossmember does not fit an '86 Cutlass 2-door model.
Date published: 2024-04-19
I've got a '78 Cutlass that came with a 305 SBC/ TH200 from the factory. Why would it not fit, aren't the stock X-members all the same?
The Jegs 555-640600 crossmember does not fit Cutlass Supreme chassis'.
Date published: 2024-02-22
Will it fit a box chevy 1984 chevy caprice
The Jegs 555-640600 crossmember does not fit an '84 Caprice.
Date published: 2024-02-13
Will this fit a1984 cutlass supreme
The Jegs 555-640600 crossmember does not fit Cutlass 2-door vehicles.
Date published: 2023-09-27
Will this work on my 700r4 transmission 1980 Buick LeSabre coupe 5.7 v8
The Jegs 555-640600 crossmember does not fit an '80 LeSabre.
Date published: 2023-08-30
Will this work in my 86 Monte as with a 3 speed Saginaw standard transmission
The Jegs 555-640600 cross member is a direct bolt in for an '86 Monte Carlo.
Date published: 2023-07-27
Will this crossmember fit on a 1984 cadillac fleetwood with a 350 transmission
The Jegs 555-640600 crossmember does not fit an '84 Cadillac.
Date published: 2023-05-31
Will it fit a 1984 oldsmobile delta 88
The Jegs 555-640600 crossmember does not fit an '84 Delta 88.
Date published: 2023-03-01
Modular Transmission Conversion Kit 1967-69 Chevy Camaro & Pontiac Firebird TH350, Powerglide, TH700R4, 4L60E, Muncie 4-Speed Red
Transmits more power to the rear tiresFits 1958-1988 chevy powerglide, th350, th400, 700r4, all borg-warner, muncie, saginaw, chrysler 4 speed, and doug nash 5 speedIncludes (1) mount, (4) 7/16 in.-14 x 1 in. hex head bolts, (4) 7/16 in. lock ...
Some parts are not legal for use in California or other states with similar laws / regulations
Motor Vehicles
WARNING: Motor vehicles contain fuel, oils and fluids, battery posts, terminals and related accessories which contain lead and lead compounds and other chemicals known to the State of California to cause cancer, birth defects and other reproductive harm. These chemicals are found in vehicles, vehicle parts and accessories, both new and as replacements. When being serviced, these vehicles generate used oil, waste fluids, grease, fumes and particulates, all known to the State of California to cause cancer, birth defects, and reproductive harm.
Tools:
WARNING: Some dust created by power sanding, sawing, grinding, drilling, and other construction activities contains chemicals known to the State of California to cause cancer and birth defects or other reproductive harm. Some examples of these chemicals are: lead from lead-based paints, crystalline silica from bricks and cement and other masonry products, and arsenic and chromium from chemically treated lumber. Your risk from exposure to these chemicals varies, depending on how often you do this type of work. To reduce your exposure, work in a well-ventilated area and with approved safety equipment, such as dust masks that are specially designed to filter out microscopic particles.
Electrical Cords
WARNING: The wires of these products contain chemicals known to the State of California to cause cancer and birth defects or other reproductive harm. Wash hands after handling.